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Transfer of Training and Retroaction 

A Comparative Study 



A DISSERTATION 

SUBMITTED TO THE FACULTY 
OF THE 

Graduate School of Arts and Literature 

IN Candidacy for the Degree of 

Doctor of Philosophy 

(Department of Psychology) 

by 
LOUIE WINFIELD WEBB 



A Private Edition 

Distributed By 

The University of Chicago Libraries 



The Trade Edition Is Published by 

The Psychological Review Company, Princeton, N. J. 
As Psychological Monograph, No. 104 

1917 



TTbe tlniversit)? of Cbtcago 



Transfer of Training and Retroaction 
A Comparative Study 



A DISSERTATION 

SUBMITTED TO THE FACULTY 
OF THE 

Graduate School of Arts and Literature 

IN Candidacy for the Degree of 

Doctor of Philosophy 

(Department of Psychology) 

BY 

LOUIE WINFIELD WEBB 



A Private Edition 

Distributed By 

The University of Chicago Libraries 



The Trade Edition Is Published by 

The Psychological Review Company, Princeton, N. J. 
As Psychological Monograph, No. 104 

1917 



V 



^ 



\0^ 



The Uui^srsUf 
NOV K »W 




ACKNOWLEDGISIENT 

My main obligation for advice and suggestion in this experi- 
ment is due to Professor Harvey A. Carr. I owe much to Pro- 
fessor James R. Angell for encouragement and inspiration. I 
wish to express my sincere thanks to the many subjects who gave 
of their time and patience throughout the course of the ex- 
perimentation. 



CONTENTS 
I. Introduction. 

II. Transfer of Training. 

A. Dependence of Transfer upon the Character of 

the Second Problem. 

B. Dependence of Transfer upon the Character of 

the First Problem. 

C. Dependence of Amount Saved upon Direction of 

Transfer. 

D. Locus of the Transfer in the Learning Curve. 

E. Selective Effect of Transfer upon Types of Error. 

F. Summary. 

G. Theoretical Discussion. 

III. Retroaction. 

A. Retroactive Effect of a Certain Activity upon Vari- 

ous Other Activities. 

B. Retroactive Effect of Various Activities upon the 

Same Process. 

C. Summary. 

D. Theoretical Discussion. 



TRANSFER OF TRAINING AND RETROACTION 
I. INTRODUCTION 

This study deals with the problems of transfer of training, 
retroactive inhibition, and their possible interrelations. The 
maze activities were utilized as the material of study, and both 
human and animal subjects were employed in the experimenta- 
tion. 

The term 'transfer of training' has long been in use in educa- 
tional literature. The question usually considered in reference 
to this idea is, whether or not the learning of one problem aids, 
hinders, or has no effect upon the acquisition of a second prob- 
lem. We shall employ additional terms to designate the three 
possible effects above mentioned. The term 'positive transfer' 
will be used to denote the results obtained when the learning 
in the first situation aids the learning in the second situation. 
'Negative transfer' will be the term used to denote the results 
obtained, when the learning in the first situation hinders the 
mastery of the second problem. There is also the possibility 
that the first learned material will have no effect upon the ac- 
quisition of the new material. In this case transfer of training 
will not be present. Results obtained in this last named instance 
will be referred to under the designation 'absence of transfer.' 

The term 'retroactive inhibition' has been definitely recognized 
since the experiments of Miiller and Pilzecker,^ and this term 
refers to the disturbing effect that the learning of a second prob- 
lem has upon the retention of material previously acquired. As 
with transfer, there are three possible retroactive effects. The 
second acquired material may aid, hinder, or have no effect upon 
the retention of the first learned problem. We shall use the term 
'retroaction' to refer to any possible effect that a second activity 
may have upon the retention of a first problem. The term 'posi- 

' Miiller and Pilzecker. Experimentelle beitrage zur Lehre vom Gedacht- 
niss. Ztsch. f. Psychol., 1900, Ergzbsbd. I. 



2 LOUIE U INFIELD WEBB 

tive retroaction' will be used to refer to the results when the 
second learned problem aids in the retention of the first problem. 
When the second problem interferes with the retention of the 
problem previously acquired, this result will be termed 'negative 
retroaction'; this last described condition is what Miiller and 
Pilzecker termed retroactive inhibition. There is the further 
possibility, as was found by DeCamp," that the second learned 
problem may have no effect upon the retention of the first prob- 
lem. Such a case will be referred to by the term 'absence of 
retroaction.' 

We believe that all three results have been obtained in the 
experiments on transfer. A positive or beneficial efifect has been 
the usual result, and practically all the writers agree on the term 
positive transfer to denote this result. The term negative trans- 
fer seems to be employed to refer sometimes to the absence of 
any efifect and sometimes to an inhibitive or detrimental efifect. 
Terms are needed to discriminate between these two cases. Ex- 
periments on retroaction report but two types of results, either 
an interference or a lack of any efifect. However, the possibility 
of all three efifects must be recognized, and distinct terms are 
needed. Those suggested by this paper serve this need, and 
give the added advantage of a uniform terminology in compar- 
ing our two problems. 

The maze was chosen as the basis of these experiments for 
three general reasons, (i) To study the phenomena of transfer 
and retroaction in a type of human activity somewhat dififerent 
from those previously used, viz., an activity of a sensori-motor 
and adaptive character. (2) To investigate these phenomena in 
the animal as well as in the human realm. (3) To determine the 
essential similarity or difference between human and animal or- 
ganization for these aspects of the learning process. The value 
of the maze problem for these purposes is obvious. 

I. The experiments with human subjects on the problem of 
transfer have been rather adequately reviewed by Thorndike,* 

^DeCamp: A Study of Retroactive Inhibition. Psych. Rev. Men. Sup. 
vol. 19. 

3 Thorndike : Educational Psychology, Vol. 2. 



TRANSFER OF TRAINING AND RETROACTION 3 

and Coover.* There is no intention here of repeating this type 
of work. The object we have in view is simply to present a 
sufficient review of the literature to contrast the materials and 
methods previously used with those employed in this experiment. 
Our purpose is well served by following Coover's analysis. He 
classifies the experiments on transfer under the following topics, 
(i) Habituation to distraction. Vogt's work on testing the ef- 
fect of reacting to a metronome, and reciting series of letters, 
upon the simultaneous activity of adding a column of figures 
serves as an example of this type of experiment. (2) Sensitivity. 
An illustration of this class is afforded by the work of Epstein, 
who sought to determine the influence of sound stimulations 
upon the acuity of simultaneous visual processes. (3) Discrimi- 
nation. Bennett tested the effect of training in discrimination 
of shades of blue upon the dscrimination of shades formed by 
a mixture of two colors, and upon discrimination of pitch differ- 
ences. (4) Association. Thorndike and Wood worth tested the 
effect of training in estimating areas, weights and lengths upon 
estimations of various other areas, lengths and weights, of a 
dift'erent character. (5) Reaction. Thorndike investigated the 
eft'ect of training in marking out words containing both the let- 
ters e and .? upon the ability to mark out words with different 
pairs of letters, such as e-g, i-t, s-p, e-r; the length of the lines, 
size of type, and style of reading matter varied in the test series 
from that which was employed for the same items in the train- 
ing series. The effect of the above mentioned training was also 
tested upon marking out misspelled words and words containing 
the capital letter A. Bergstrom reports some experiments on 
discriminative reactions, which showed interference. He tested 
the effects of training in the sorting of cards by one method 
upon the ability to assort cards by a different method. (6) Mem- 
ory. The work of James in memorizing poetry, Ebbinghaus' 
work on memorizing nonsense syllables, the experiments of Ebert 
and Meumann with nonsense and other material, serve as illus- 
trations of the work done in this field. (7) Voluntary control. 

*Coover: Formal Discipline from the Standpoint of Experimental Psy- 
cholog}'. Psych. Rev. Mon. Sup. Vol. 20. 



4 LOUIE WINFIELD WEBB 

Judd and Cowling tested the effects of drawing an imaged form 
with the eyes open upon the abihty to draw the image with the 
eyes closed. 

We wish to offer here criticism of one aspect of Coover's 
analysis. We are inclined to believe that his classification is 
too broad. We doubt the advisability of including under the 
term transfer of training his first and second headings. These 
have to do with the effect that one activity has upon a simul- 
taneous activity. Undoubtedly some sort of interaction does 
obtain between two such activities. Transfer of training, how- 
ever, implies the utilization of the effects of training or a learn- 
ing process upon some subsequent activity. Coover's two classes 
deviate from this definition in two respects. The first activity 
hardly involves anything that may legitimately be termed train- 
ing or learning, and the effect is upon a simultaneous and not 
upon a subsequent process. Coover, however, discusses these 
experiments under the topic of 'Formal Discipline,' but to our 
mind, the two terms formal discipline and transfer of training, 
have been used as synonyms in the literature. 

In further considering this classification, it appears to us that 
three divisions, which Coover does not mention, may be added. 
(8) Attention and Reproduction. Coover used in his experi- 
ments some of the methods and materials mentioned under the 
above headings, such as marking out words, estimating weights, 
and discrimination problems. He also performed experiments 
with other materials that we would classify under another head- 
ing. In the experiments on attention Coover tested the eft'ects 
of training in activities which involve a large amount of atten- 
tion such as, tachistoscopic work, learning 12-letter-rectangles, 
reactions to sounds, and memory training, upon such activities 
as reactions to sounds, marking out a's and o's, card sorting, 
memory of visual signs, trains of ideas, tapping, and many other 
activities. The difference in attention was noted between the 
training work and the testing series. In the reproduction experi- 
ments the effect of training in sound discrimination was tested 
upon such activities as recognition of one or two letters, repro- 
duction of letters, sound discrimination, and memory for visual 



TRANSFER OF TRAINING AND RETROACTION 5 

symbols. (9) Cross education. The experiments on cross edu- 
cation note the transfer to one hand or foot from a training of 
the other hand or foot. The experiments of Davis, ^ and John- 
son" with tapping; those of Woodworth^ on hitting a dot with 
a pencil; the ones of Swift on tossing balls; and those of Starch 
on tracing an outline seen only in a mirror are cited as illustra- 
tions of work in cross education. (10) Sensori-motor learning 
of an adaptive character. At the meeting of the American 
Psychological Association, 1915, Dr. Frank N. Freeman re- 
ported some tests made by him on transfer in sensori-motor 
learning. This is a study of mirror drawing. The apparatus 
was so constructed that it was modifiable in such a way as to 
vary the conditions indefinitely. The problem in these experi- 
ments was to test the effect of learning to connect six dots with 
a pen, with the mirror in one position, upon learning to connect 
the six dots with the mirror in another position. 

There are marked variations in the results from the various 
experiments on transfer of training. In summarizing the ex- 
periments, following his review, Coover interprets the results 
in most instances as evidence of positive transfer; he recognizes, 
however, several instances of negative transfer. Thorndike, in 
his review of the literature, gives the reader a strong impression 
that the evidence for positive transfer is rather weak. This is 
indicated by the following quotation. "These experimental facts 
as a whole, like those concerning memory, leave a rather con- 
fused impression on one's mind, and resist organization into any 
simple statement of how far the improvement wrought by special 
practice spreads beyond the function primarily exercised.""^ We 
are of the opinion that some of the experiments demonstrate the 
existence of a decided positive transfer. Bennett showed that 
training in memorizing poetry improved memory for digits and 
names of places; Ebert and Meumann proved that training for 
nonsense syllables improved the memory for letters, numbers, 
words, poetry, prose and optical symbols. Some of the results 

^ Davis : Researches in Cross-Education. Yale Studies, Vol. 4. 
8 Johnson : Researches in Practice and Habit. Yale Studies, Vol. 4. 
7 Cited by Thorndike. Op. Cit. p. 366. 
sop. Cit. p. 416. 



6 LOUIE W INFIELD WEBB 

also demonstrate the existence of negative transfer. A splendid 
illustration of this is found in the work of Bergstrom, wherein 
he showed that the training in the sorting of cards by one 
method interfered with the sorting of cards by a new method, 
and that in learning series of nonsense syllables successively, the 
time becomes progressively longer if the series possess recurring 
elements. Further, we believe that some of the results indicate 
an absence of transfer. An illustration of this is taken from 
the work of Sleight as reviewed by Thorndike^ : Sleight's re- 
sults show that training in memorizing poetry has very little, 
if any, effect upon the memorizing of tables of figures or prose. 
James interpreted his own experiments on memory as evidence 
of an absence of transfer. Some of Thorndike and Wood- 
worth's experiments give evidence of little or no transfer. 

We have seen that the materials employed in the experiments 
on transfer vary from those of a purely ideational character, 
such as memorizing poetry or nonsense syllables, to those having 
less and less of an ideational character; in some of the experi- 
ments, such as those dealing with visual and auditory discrimi- 
nations, the sensory elements predominate; there are also 
experiments dealing mainly with material of a sensori-motor 
character such as those of Freeman referred to above. The 
material used in our experiment is more nearly like that em- 
ployed by Freeman. The maze activities are essentially sensori- 
motor in character. The sensori-motor element predominates 
in mastering a maze situation. This is the universal conclusion 
of all experimenters with such animals as the white rat. The 
rational element is present with human subjects, but it is recog- 
nized that these ideational activities function with little effective- 
ness in the mastery of the problem. The sensory elements em- 
ployed are what James calls resident sensations. Under the 
conditions of our experiment the effective sensory factors are 
tactual and kinaesthetic in character. 

There have been no published experiments dealing specifically 
with transfer in the animal field; neither has the maze activity 
been utilized in the study of this phenomenon with human sub- 
s' Op. cit, p. 379- 



TRANSFER OF TRAINING AND RETROACTION 7 

jects. Perrin^° used the same subjects in the learning of the 
several mazes in his experiments, but he made no definite report 
of the transfer effect. 

There have been no experiments on retroaction which em- 
ployed sensori-motor activities. Only three important studies 
with human subjects have been reported. Miiller and Pilzecker^^ 
investigated the retroactive effect of memorizing nonsense sylla- 
bles and observation of pictures upon the retention of pre- 
viously learned material. They reported that such subsequent 
activity exerted a negative or inhibitive effect upon the 
retention of the first learned series. DeCamp^- investi- 
gated the retroactive effect of such activities as memo- 
rizing nonsense material, multiplying a series of numbers, 
the solution of various problems, and playing chess, upon 
the retention of previously mastered material, and he decided 
that no retroactive effect was present in his experiments. Heine^^ 
repeated Miiller and Pilzecker's experiments and verified the for- 
mer results; she also discovered negative retroaction between 
the letters of the syllables ; she made further tests for retroaction 
employing recognition instead of learning, and here she failed 
to secure evidence to prove the presence of a retroactive eft'ect. 

It will be noted that Miiller and Pilzecker investigated the 
retroactive effect of two similar activities of an ideational char- 
acter. DeCamp also used activities of an ideational character, 
and employed dissimilar as well as similar activities. We shall 
also use two similar activities in our experiments — the effect of 
one maze activity upon another — but shall employ sensori-motor 
activities rather than those of an ideational character. This 
difference of material is significant because of a possible differ- 
ence in the stability of the two types of activity. Results ob- 
tained from stable material may thus indicate that the existence 
or degree of negative retroaction may depend in part upon the 

i** Perrin : An Experimental and Introspective Study of the Human Learn- 
ing Process in the Maze. Psych. Rev. Mon. Sup. Vol. 16. 
"Op. cit. 

12 Op. cit. 

13 Heine : tJber Wiedererkennen und riickwirkende Hemmung. Ztsch. f. 
Psychol., 1914, Band 68. 



8 LOUIE WIN FIELD WEBB 

Stable character of the activities employed in the experimentation. 

The results of DeCamp suggest the further possibility that 
retroaction may be in part dependent upon the similarity of the 
two activities employed. For this reason we decided that it 
would be better to utilize two highly similar processes. Our 
method deviates from that of DeCamp, and Miiller and Pilzecker 
in two other important respects: (i) The temporal relation of 
the two activities. Their first activity is learned with continuous 
trials in a single sitting, while the second work is performed 
within five to fifteen minutes subsequently. Rats of necessity 
master the two mazes with a distribution of trials extending over 
several weeks, with at least a day's interval between the comple- 
tion of the first maze and their introduction to the second. The 
same distribution of effort was maintained for the human sub- 
jects in order to secure comparable results in the two cases. 
(2) The method of measuring retention. The previous experi- 
ments measured the amount retained after the interpolation of 
the second activity by the usual method of verbal reproduction. 
Such a method is impossible with the maze problem. In our 
experiment retention was necessarily measured by the relearning 
method. 

2. Our second purpose is justified by the fact that there has 
been little or no systematic work done on either problem in the 
animal field. 

Many of the early workers in the animal field incidentally 
noted and commented upon the presence of transfer when animals 
used on one problem were employed on some other task.^* There 
are but three systematic works on this subject with which the 
author is acquainted. One w^as reported by Mr. H. H. Wylie 
at the meeting of the American Psychological Association, 191 5. 
He trained white rats to respond to a certain stimulus, e. g. light 
or pain, in a given situation. After this habit was well estab- 
lished, the animals were taught to respond to a different stimulus 
in the same situation, and the degree of transfer between these 

1* Watson has given an excellent review of the literature in this field in 
his te.xt, "Behavior, An Introduction to Comparative Psychology." Chapter VI. 



TRANSFER OF TRAINING AND RETROACTION 9 

two highly similar situations was measured. Hunter^^ demon- 
strated with white rats that the acquisition of an auditory-motor 
habit interfered in the formation of a new habit of opposite 
character. Pearce" has demonstrated the same result, dupli- 
cating the conditions of Hunter, but employing visual-motor 
habits. 

Within the knowledge of the author of this paper, no experi- 
ments on retroaction in the animal field have been reported. 

3. We also wished to determine whether the laws and condi- 
tions of transfer and retroaction are the same for both humans 
and animals; whether human and animal organizations are es- 
sentially identical in kind. 

Thorndike," in elaborating the laws of learning, maintains 
the validity of the above proposition. Most Comparative Psy- 
chologists would subscribe to this belief, but it is a belief or 
generalization which represents to a large degree a working 
hypothesis, the testing of which Comparative Psychology recog- 
nizes as one of its main tasks. Thus far Comparative Psychology 
has demonstrated the hypothesis in many respects, e. g. both 
humans and animals can learn, and both can learn by the same 
method. However, the proposition is not completely demon- 
strated in every respect, and we wish in these experiments to 
test the hypothesis in two additional phases, transfer of training 
and retroaction. 

To test the proposition that the laws of learning are the same 
for humans and animals, it is advisable to secure comparisons 
where the problems and conditions are as similar as possible. 
Many more comparative statements and generalizations could 
be made from the work already done, if similar situations had 
been used. So far as the author is aware, there have been only 
three experiments reported, wherein the identity of the problems 
and situations was maintained to an important degree. Hicks 
and Carr^* compared the ability of white rats and humans in 

15 Hunter : The Interference of Auditory Habits in the White Rat. Jour. 
Animal Behav., Vol. 7, No. i. 

16 Pearce : A Note on the Interference of Visual Habits in the White Rat. 
Jour. Animal Behav., Vol. 7, No. 3. 

17 Op. Cit, p. I2f. 

18 Hicks and Carr : Human Reactions in a Maze. J. Animal Behav., Vol. 2. 



10 LOUIE WIN FIELD IV EBB 

learning the maze problem. The two problems were similar in 
kind, but the mazes were not identical in pattern, and some other 
conditions differed so that their situations were not as similar 
as they might have been. Hunter^^ was the first one to study 
humans and animals with conditions and problems identical. He 
tested animals and children on the problem of delayed reaction. 
The identity of the two situations was maintained as far as 
possible, and he found that the period of delay in the reaction 
could be lengthened as he ascended the animal scale from rodents, 
dogs, primates, and children. Pechstein^° has studied various 
methods of motor learning, using animals and humans in learn- 
ing the maze. His maze patterns, his technique and method of 
procedure were similar to a marked degree. Our experiment 
is only one more step of the many that are needed in the com- 
parative field to test the above hypothesis. The effort was made 
to have the situations as comparable as possible, and it is believed 
that another bit of evidence is added by this study towards the 
solution of this important problem. 

In the experiments with the rats two adjustable mazes were 
used. They were the same in size, 4' x 3^8'^ x 6". These mazes 
were made of 3^'^ stuff and were covered with glass. Each 
maze was placed upon a frame about eighteen inches high. The 
runways and the cul de sacs were four inches in vv'idth. The 
partitions within the mazes were made of galvanized sheet iron, 
and were set in brass supports, so that they were easily moved 
back and forth. This construction gives large possibilities of 
altering the location of the cul de sacs in relation to the true 
path. Six different maze patterns were thus constructed and 
utilized in the experiments with rats. These patterns will be 
hereafter designated as Mazes A, B, C, D, E, F. They are 
represented in Figures i to 6. 

The mazes used for the human experiments are known as 
'pencil mazes.' Two of these were made from solid aluminum 

13 Hunter: The Delayed Reaction in Animals and Children. Behav. Mon. 
Vol. 2. 

20 Pechstein : Whole vs. Part Methods in Motor Learning. Psych. Rev. 
Mon. Sup. No. 99, Vol. 23. 



TRANSFER OF TRAINING AND RETROACTION n 

castings and two from solid brass castings. The cul de sacs 
and the true runways were milled out of the castings, and were 
^" wide by ^'' deep. The partitions were j4'^ wide, and the 
outside dimensions were SH'^ ^ 5/4 "'• ^^t four patterns were 
employed with human subjects, and these are designated as pencil 
mazes A, B, C, D. These four duplicate exactly, except on a 
reduced scale, the patterns of mazes A, B, C, and D respectively 
used with the rats. They were identical as to the location of 
runways and the cul de sacs. Each section of the true path, 
each turn in the true path, and each cul de sac had the same 
relative position in each type of maze. Not only did we have 
identity of maze patterns, but we endeavored to have the tech- 
nique and method of experimentation, which will be described 
later, as similar as possible. The exact duplications of maze 
patterns and the identity of method of procedure for rat and 
human subjects were adopted in order to achieve our third ob- 
ject mentioned above, the comparison of human and animal re- 
sults upon identical problems. 

The rats used in this experiment were thoroughly tame, having 
been fed for a week in the maze before the experimentation be- 
gan. The animals were kept in the same room where the experi- 
ment was performed, and the location and conditions of their 
living cage were not changed during the experimentation. When 
the cages were cleaned, this work was always done after the 
experiment of the day was finished, thus giving the rats twenty- 
four hours to become adjusted to the disturbance. The work 
of each day was done in the late afternoon. Before the experi- 
mentation began the window shades were lowered and the electric 
lights were switched on, thus giving uniform lighting conditions 
throughout the experiment. The animals were run under a 
stimulus of normal hunger. Each animal was given one trial 
per day for the first four days and two trials per day thereafter 
until the maze was mastered. At the end of the first trial the ani- 
mal was allowed a bite or two or food, and then immediately was 
given his second trial. When the group had finished the day's 
work, they were allowed to eat for seven minutes of a diet of 
bread and milk; at intervals sunflower seed was added to the 



12 LOUIE IVINFIELD WEBB 

diet. In the experiment on transfer, after each subject had 
mastered the first maze, he was transferred to the second maze 
on the following day. The same method of procedure obtaining 
in the learning of the first maze was continued during the mas- 
tery of the second maze. During the period in which the rats 
were not running the maze, they were each day taken from the 
cage and allowed to run on the top of a table for exercise. They 
were fed as during the experiment outside of the cage. This 
was done in order to maintain the normal conditions of the 
experiment and to obviate any disturbance until after the tests 
for retention were given. The results presented in this paper 
were obtained from one hundred and thirty-six white rats. The 
animals were from seven to twelve weeks old at the beginning 
of the experiment; they were in good condition and remained 
so throughout the tests. Males and females were in each of the 
groups in the separate parts of the experiment. 

The human subjects upon entering the room in which the 
experiment was conducted, were seated at one side of a table. 
On this table the pencil maze was placed. Light strips of wood 
were nailed to the table at each side of the maze to prevent any 
movement when a subject was working on it. On the table, and 
covering the maze, was a frame one foot high on one side and 
one and one half feet high on the other side. The frame was 
eighteen inches wide and sixteen inches deep, and was covered 
with a heavy black cloth which hung loosely on the side towards 
the subject, and adequately hid the maze from his sight. The 
higher end of the frame opposite the subject was uncovered. 
This arrangement left the maze in full view of the experimenter, 
so that all errors were easily noted. This method was adopted 
in order to eliminate the disconcerting effect of a blind-fold, 
and to secure a comparable situation as to vision for humans 
and animals. The human subjects traced the maze with a stylus 
made of hard rubber. A shoulder about one inch from the lower 
end prevented the hand from slipping and coming in contact 
with the maze. The lower end of the stylus was 3/16" in di- 
ameter and the pathway, being Y/^" wide, permitted easy contact 
with both sides. Each subject was given the following instruc- 



TRANSFER OF TRAINING AND RETROACTION 13 

tions: "Please put your hand under the cover; grasp the stylus 
and hold it as erect as possible with comfort; keep the stylus 
in the groove, and explore the area assigned until you are told 
to stop. Use any method you desire and think as much about 
the problem as you wish during the experiment, but do not try 
to draw the area and try not to think about the problem during 
the interval between successive trials." At the end of the run 
there was an opening in the pencil mazes, corresponding to the 
food box in the other mazes. This enabled the subjects to know 
when the end was reached, and thus they had to be told when 
to stop working for only one or two trials. One trial per day 
was given to each subject for the first four days and two trials 
per day thereafter until the problem was mastered. Sunday 
necessarily had to be omitted with the human subjects. When 
each subject had mastered their first maze, the following day 
he was transferred to the second maze. None of the subjects 
knew that the experiment was dealing with the problem of trans- 
fer and retroaction, and in no instance was a subject told that 
the maze had been changed; he discovered the new situation by 
going through it and noting the disturbance. A large part of 
the subjects were naive, and knew nothing of the maze problem. 
Here again we notice the similarity of the procedure for humans 
and animals; each had to discover the new problem empirically. 
When a human subject finished the first part of the experiment, 
he was asked to come back at some later specified time for an- 
other part of the experiment. Each subject was requested not 
to think about the problem any more than possible, nor to try 
to draw the maze pattern during the interval. In the test for 
retention, the same instructions were given, and the same condi- 
tions were maintained as were used in the first part of the experi- 
ment. At no time was a subject told that this other part of 
the experiment was to be a test for retention. The subjects, 
fifty-two in number, were graduate and undergraduate students, 
all of whom were studying psychology in the University of Chi- 
cago. There were both men and women in each of the groups 
that were used in the various parts of the experiment. 

Individual time and error data for each trial were recorded. 



14 LOUIE WINFIELD WEBB 

The time in seconds was measured with a stop watch. The time 
for each trial was counted from the moment the subject entered 
the maze until he reached the entrance to the food box. No 
record of the distance traversed was kept, as this was practically 
impossible under the conditions here maintained. We agree with 
Mrs. Hicks^^ in her emphasis upon the distance traversed, as a 
criterion for measuring the learning process in a maze situation. 
However, our method of counting errors overcomes, to a large 
extent, this deficiency; each section of the true path, no matter 
how short, was counted an error in retracing. The unit of error 
was one section of the pathway. Each entrance into a cul de sac, 
whether for all or part of its length, each retrace over the whole 
or a part of a section of the true pathway, was counted an error. 
The errors due to entering a cul de sac while going forward, 
the errors due to entering a cul de sac while returning home, and 
the errors due to retracing the true pathway, were kept sepa- 
rately. The criterion of mastery was four perfect trials out of 
five, and in these five trials not more than two errors were 
allowed. 

The comparableness of the technique and methods of pro- 
cedure for both types of subjects is obvious. The maze patterns 
are identical, the mazes for the humans being duplicates of those 
used with the rats, with the exception of a difference in size. 
The methods of recording the data were the same; the distribu- 
tion of effort is practically the same. Watson" has shown that 
rats make very little use of vision in mastering the maze problem ; 
the rats have eyes, but do not use them in this situation. With 
the technique here maintained, it can be said that the humans 
have eyes but do not use them in this situation, and further the 
disconcerting effect of a blind-fold is absent. Both humans and 
animals come to the problem naively. The humans were not 
informed as to the situation; they had to discover their problem 
as did the rats. This last condition was more fully maintained 

21 Hicks : The Relative Value of the Different Curves of Learning. Jour. 
Animal Behav., Vol. i. 

22 Watson : Kinaesthetic and Organic Sensations. Psych. Rev. Mon. Sup. 
Vol. 8. 



TRANSFER OF TRAINING AND RETROACTION 15 

with the human subjects who learned pencil mazes C and D. 
These subjects knew nothing of the problem until after they 
worked on it. The groups that learned pencil mazes A and B, 
involving transfer, were graduate students in Psychology and 
were well enough acquainted with the experiments being carried 
on in the laboratory, to know that this experiment was dealing 
with the maze problem. The results of the naive and sophisti- 
cated groups were compared, and only minor differences, such 
as can be accounted for in terms of chance differences, were 
noticeable. However, all of the human subjects came to the 
transfer and the tests for retention naively, as did the rats, as 
nothing was said to any of the subjects to indicate the changes. 
During the interval that the rats were not running the maze, 
the conditions of exercise and feeding were not changed, so nor- 
mal conditions obtained when they returned to the maze for 
testing retention. The human subjects went about their normal 
activity, and were asked not to think about the problem, nor to 
try to draw the area during the interval. Thus it is observed 
to what extent we endeavored to keep the conditions similar for 
the two types of subjects. By these means our third purpose 
mentioned above is well served, and our conclusions in comparing 
the transfer and the retroactive effects on humans and rats are 
rendered more valid. 



II. TRANSFER OF TRAINING 

A. Dependence of Transfer upon the CharactI'R of the 
Second Problem. 

The object of the first experiment is to determine to what 
extent the nature and degree of transfer is a function of the 
second problem. 

In educational literature there has been much discussion rela- 
tive to the question of the general spread of training. The class- 
ical argument has been that the study of Latin or Greek improves 
the intelligence of the student in such a manner that said learner 
will be able to acquire more easily any other subject he there- 
after studies. This statement seems to imply that the existence 
of any transfer effect in subsequent situations depends wholly 
upon the character of the previous training. The other side of 
the question must also be recognized, viz. that the functional 
efficacy of classical training may depend in large part upon the 
nature of one's subsequent mental activity — that it may have 
more effect in the life activities of a lawyer than of an electrical 
engineer. Our first experiment was designed to solve this latter 
question, not that we experimented with the Classics and other 
strictly intellectual subjects, but rather that we were concerned 
with the solution of the problem in the realm of motor learning. 

In terms of mazes the problem is readily illustrated. Several 
groups of subjects first learn a common maze A, and each group 
subsequently learns a different maze. One group is thus trans- 
ferred from Maze A to Maze B, another from A to C, one from 
A to D, another from A to E, and one from A to F. If the 
nature and degree of the transfer is wholly a function of the 
first maze, fairly uniform results should be secured for all groups. 
The group differences should be only such as can be attributed 
to chance or group factors. Marked variations in the results 
would indicate, on the other hand, that the nature and degree 
of transfer is in part a function of the nature of the second maze. 



^ TRANSFER OF TRAINING AND RETROACTION i? 

In our experiment six groups of subjects first learned Maze A. 
These groups comprised a total of 54 rats and 21 humans. A 
group of nine rats and a group of five humans were then trans- 
ferred to Maze B; a group of eleven rats and a group of six 
humans subsequently learned Maze C; a group of six rats and 
one of five humans were transferred to Maze D; a group of eight 
rats then mastered Maze E, and a group of nine rats subsequently- 
learned Maze F. 

The transfer effect is measured by the difference between 
'original learning' and 'transferred learning.' By original learn- 
ing we mean the acquisition of a maze by a group of subjects 
without previous maze experience. By transferred learning we 
refer to the mastery of a maze by a group with a previous maze 
experience. Thus control groups were necessary for jVIazes B, 
C, D, E, F, in order to secure data on the original learning. 
These control groups consisted of 20 rats and 10 humans for 
Maze B, II rats and 10 humans for Maze C, and 13 rats and 11 
humans for Maze D. No human subjects were employed on 
Mazes E and F, and the control groups for these mazes consisted 
of 16 and 15 rats respectively. 

Table i presents the results in the absolute terms of averages 
for our first experiment. The transfer effect was measured sep- 
arately in terms of trials, errors and time, thus giving us three 
criteria of measurement. The group averages, together with the 
average deviation, for the original and the transferred learning 
are given for each of the criteria. The letters in the table indi- 
cate the records for the several mazes ; thus B indicates the record 
for the original learning of that maze, and A-B denotes the 
transferred learning of the same maze. The A in connection 
with the A-B means that Maze A constituted the previous maze 
experience of the group. The symbol Sav. refers to the average 
amount saved for each group and these figures thus measure 
the transfer effect for each group. Table 2 states the saving 
in relative or percentage terms. These percentages of transfer 
are secured by dividing the absolute amount saved for any maze 
by the figure measuring the original mastery of that maze. If 
12 trials are saved In transferring to Maze B, while 15 trials were 



l8 LOUIE WINFIELD WEBB 

Table i. Comparative Records of Original and Transferred Learning. 







Rats 






Trials 


Errors 


Time 


B 


56.2±I4.7 


224. ±71.8 


2468.6±i6i4.3 


A—B 


I2.9± 9. 


3i.8±20.3 


400.5 ± 200.2 


Sav. 


43-3 


192.2 


2068.1 


C 


45.7±I4.5 


238.5±76.9 


2939.4±2504.5 


A-C 


i8.3±i4.2 


I29.3±78.3 


1902.2 ±1261. 8 


Sav. 


274 


109.2 


1037.2 


D 


i6.7± 8.1 


I53.6±5i. 


2777.3^1272.4 


A—D 


5.2± 44 


3I.2±20.6 


487. 1 ± 218.6 


Sav. 


"•5 


122.4 


2511.1 


E 


4.4± 2.5 


19. ± 6. 


2i3-5± 75-5 


A—E 


3-5± 1-5 


8.6± 5.9 


78. 1 ± 53-6 


Sav. 


.9 


10.4 


1354 


F 


27.9±io.i 


I28.5±39.2 


I209.8± 447-7 


A—F 


10.3 ± 6.1 


73-8±37. 


490.7 ± 294.7 


Sav. 


17.6 


54.7 
Humans 


7191 


B 


33.6±I4.3 


285.2±20S.4 


1 166. ±514.2 


A—B 


io.8± 5.9 


32.4+ 13.7 


149.4+ 54-7 


Sav. 


22.8 


252.8 


1016.6 


C 


38. ± 9-8 


i33-7± 43-8 


736.4± 124.2 


A—C 


30.5±i3- 


io6.8± 44-5 


52i.5±i68.i 


Sav. 


7-5 


26.9 


214.9 


D 


ii.6± 6.9 


203. ±176. 


773.5 ±498. 


A—D 


5-6± 3.3 


II. ± ID. 


87.2± 64.6 


Sav. 


6. 


192. 


686.3 



expended in its original mastery, it is evident that the effects 
of the transfer represent a saving of 80%. The symbols of this 
table have the same meaning as in Table i. 

Upon the basis of the data presented in these tables, we are 
able to make the following conclusions, which will be illustrated 
and discussed. 

I. The nature of the transfer is positive for all five pairs of 
mazes for both humans and animals, and by all three criteria 
of measurement. In no instance is there any evidence of nega- 
tive transfer. 

The data of Tables i and 2 substantiate this conclusion. An 



TRANSFER OF TRAINING AND RETROACTION 19 

Table 2. Average Percentage of Saving in Transfer. 





Rats 








Trials 


Errors 


Time 


A—B 


77.08 


85.81 


83.77 


A—D 


69.02 


79-71 


90.42 


A— £ 


19.91 


54.63 


63.40 


A—F 


63.01 


42.78 


59-44 


A—C 


57.85 

Humans 


46.10 


34-94 


A—D 


51.98 


94.58 


88.73 


A—B 


67.86 


88.64 


67.18 


A—C 


1974 


20.20 


29.18 



examination of Table i shows that the averages of the original 
mastery for all three of the criteria are larger than for those 
of the transferred learning in every one of the twenty-four 
possible cases of comparison. It is observed in Table 2 that in 
every instance of measurement, in the five cases with the human 
subjects and the three cases with the rat subjects, a considerable 
percent of saving is shown to exist. It will be observed that 
the lowest percentage of transfer measured by trials is a fraction 
over 19%, by errors the lowest percentage is 20%, and by time 
the lowest record is 29%. From the lowest records, the per- 
centage saved runs up as high as '/y% for trials, 94.5% for 
errors and 90% for time. 

These differences between the records for the original and 
the transferred learning may be due to three possible causes — 
chance, group differences, or the previous maze experience of 
the transferred group. We have evidence along two lines to 
prove that chance is not playing a very important role. It will 
be noted in Table i that the average deviations are rather wide, 
due perhaps to the small number in the groups. This fact throws 
some doubt on the validity of these differences. To test this 
we figured the Probable Difference for each of the twenty- four 
instances of comparison, and in every case, with but one excep- 
tion, the actual difference was found to exceed the probable dif- 
ference. There is the further important fact of the consistency 
with which the differences occur. In the eight cases of compari- 
son of the original and transferred learning, the records for the 
transferred learning are uniformly the lower; this uniformity 



20 LOUIE WIN FIELD WEBB 

in the records can also be observed for each of the criteria of 
measurement; and it obtains for the transfer stated in both rela- 
tive and absolute terms. Considering the above facts, . we be- 
lieve that chance differences can not be regarded as the primary 
causal factor in the results here obtained. Further, the possi- 
bility of group differences functioning sufficiently to produce the 
above results is obviated by our method of selecting the groups. 
The rats were bought in lots of fifty to one hundred; these were 
mixed and the groups were selected by chance, care only being 
taken that both male and female subjects were in each group. 
Thus the possibility of having a selected group of either a good 
or a bad strain, a highly intelligent group, or a group of low 
intelligence, is eliminated. The human subjects were secured 
from the large number of students studying psychology in the 
University of Chicago, and the grouping of these was a matter 
of chance with the exception that both men and women were 
put in each group. Again, the probabilities favor our not having 
groups of good or bad strain, or groups of high or low intelli- 
gence. Mathematically, the chances favor the validity of the 
differences; the uniformity of lower records for the transferred 
learning enhances this probability manyfold; further, the factor 
of group differences was overcome by our method of securing 
the various groups. To our mind, the results of this experiment 
prove beyond doubt the existence of a positive transfer. 

The positive character of the transfer is significant in view 
of the fact that an effort was made to so arrange the relations 
between some of the maze patterns as to secure a negative effect. 
Mazes A and B were constructed on a highly similar design with 
the expectation of securing a positive effect, and we were not 
disappointed in the results. Compare Figures i and 2. In de- 
signing the other four maze patterns, we aimed to secure nega- 
tive results and in every case we failed to realize our purpose. 
The principles governing the designing of these patterns may be 
briefly mentioned. Maze C was so arranged that in transferring 
to it from A, the general direction of travel would reverse the 
older habits of the subjects. This fact is evident from a com- 
parison of the patterns represented in Figures i and 3. Maze D 



TRANSFER OF TRAINING AND RETROACTION 21 

presents such an arrangement of cul de sacs, that the older habits 
acquired in Maze A would tend to produce many cul de sac en- 
trances. Compare Figures i and 4. Simplicity, or ease of mas- 
tery governed the construction of Maze E, on the hypothesis 
that a transfer from a difficult to an easy maze might conduce 
to a high degree of confusion or disturbance. Maze F differed 
from A, both in conflicting arrangement of cul de sacs, and in 
a considerable shortening of the length of the true path. By 
a comparison of the patterns in Figures i and 6, it will be ob- 
served that in the transfer from A to F the subject must learn 
to omit the section numbered 6 to 10 which corresponds to a 
section of the true path in A. As we have stated, none of these 
arrangements operated to produce a negative transfer effect. 
However, we do not mean to assert that a negative effect be- 
tween two mazes is impossible. 

2. Transfer is a composite process consisting of both positive 
and negative elements. The acquisition of any maze may both 
hinder and aid in the mastery of a second maze, although the 
total effect is positive. 

The proof of the above proposition is found in a comparison 
of the original and transferred learning of Maze F, In the 
preceding topic we noted the relation of section 6-10 in Maze F 
to the corresponding part of Maze A. These parts are so related 
that rats trained in A should possess some tendency to enter 
section 6-10 in the subsequent mastery of F, and naturally any 
undue tendency to enter these cul de sacs will be detrimental to 
its mastery. The hypothesis that the habits acquired in A did 
exert such a detrimental effect is proven by a comparison of the 
records of the test and control groups for this section. Rats 
previously mastering A — the test group — entered this section 
much more frequently and experienced a greater difficulty in 
eliminating the tendency than did the control group — animals 
without such training. 

(i) The test group required a greater number of trials to 
eliminate this section. Our criterion of mastery was five suc- 
cessive runs without entrance. The average for the test group 
was 8.22, for the control group 6.15. Stating the values in rela- 



22 



LOUIE WIN FIELD WEBB 




FIGURE I: MAZE A. 



d 






7 
















6 








5 


4 






















1 


2 


















3 








9 






FOOD BOX 




10 
















,,. 





FIGURE. 2: MAZE B. 



TRANSFER OF TRAINING AND RETROACTION 23 




FIGURE 3: MAZE, C 



















5 












G 








B. 




3 








Z 






7 




1 








6 












9 








FOOO BOX 































FIGURE 4; MAZE, a 



24 



LOUIE liJNFIELD WEBB 



14 


13 


12 


II 


10 












G 












6 








7 








6 










5 






15 




3 


4 






16 


A 


1 


2 






17 




16 


FOOD BOX. 




19 















FIGURE. 5: MAZE E.. 



14 














10 








13 


12 


II 




7 






9 








6 




6 






















15 


1 


2 


3 


4 










16 




S 






(7 








FOOD BOX 
















> — 


- 


' ^ 





FIOURt 6; MAZE. F. 



TRANSFER OF TRAINING AND RETROACTION 25 

tive terms, the test group required 79.5% of its total trials, while 
the corresponding percentage value for the control group was 
but 22%. 

(2) The test group entered this section much more frequently. 
The average number of trials in which the test group entered 
this section was 5.88. The corresponding value for the control 
group was 5.15. The test group entered this section in 56% 
of its trials while the control group entered it but 18%. The 
animals frequently entered this section several times in the same 
trial; comparing the average number of entrances per rat, the 
values are 9.0 and 7.1 for the test and control groups re- 
spectively. 

(3) The test group made the greater number of errors in this 
section. Since our unit of error is a single runway, it was 
possible for a rat to make a number of errors in a single en- 
trance. The average number of errors per rat for the test and 
control groups were 30.4 and 24.0. Of the total number of 
errors made by the test group in mastering the maze 41.2% 
were due to this section. The corresponding value for the con- 
trol group was 10.8%. 

3. The third feature to be noticed from the above data is the 
fact that the degree of transfer is in part a function of the activ- 
ities set up in the second maze situation. 

Maze A is the constant activity, and the other five mazes are 
the varying processes of the second problem. If the transfer 
effect is mainly a function of the constant activity, the amount 
saved should be fairly uniform; the differences should be only 
such as can be accounted for by mere chance, or slight individual 
dift'erences. On the other hand, a wide divergence of results 
will indicate that the degree of transfer is in part a function of 
differences in the character of the second maze. 

Upon inspection of Table i, it is found that the amount saved 
is not uniform, but rather that the range of the variations is 
quite wide. We discover wide variations in the average amount 
saved measured by trials, errors and time. The average saving 
for trials in the rat records vary from .9 to 43.3, and in the 
human records from 6 to 22.8. The averages for errors with 



26 LOUIE WIN FIELD WEBB 

the rats vary from 10.4 to 192.2, and with the humans from 26.9 
to 252.8. Similar results are observed in the time records; the 
rats vary from 135.4 to 251 i.i, and the humans from 214.9 to 
1016.6. Likewise, the results, stated in relative terms (see Table 
2), indicate that the percentage of transfer varies with the change 
of the relation between the two activities. 

Two possible explanations can be offered to account for these 
marked variations in the degree of transfer; either these are due 
to mere chance, or they are a function of the second activity. 

The dependence of the degree of transfer upon the second 
maze activity is proven by the fact that the actual amount saved 
in each case is roughly proportionate to the original learning 
records of the five mazes. This fact is evident from an inspection 
of the data of Table i. Considering the results for trials in the 
rat records, the largest saving (43.3 trials) was secured in the 
transfer from A to B, and B was the most difficult of the five 
mazes in terms of number of trials necessary to master. Like- 
wise, the smallest amount saved (.9 trials) was secured in trans- 
ferring to E, and this maze presented the least difficulty in 
original mastery. This relation between amount saved and the 
original learning records for any maze is also evident from 
Table 2, which states the actual amount saved for any maze in 
percentage terms in reference to the data for original learning. 
If the amount saved depended absolutely upon the difficulty of 
the second maze, these percentage data should be exactly the 
same for the five pairs of mazes. Provided there is only some 
degree of correlation between the two sets of data, uniformity 
of percentage data would not obtain, but the range of divergence 
for these relative data should be much less than that for the data 
of Table i, giving the amount saved in absolute terms. Stating 
the transfer effect in relation to the corresponding learning data 
(Table 2), does decrease the range of divergence. For example, 
the saving for the rats varies between the extremes of .9 and 
43.3 trials, and this divergence is decreased to 19.91 and 77.08 
when estimated in relative terms; a better example is found by 
comparing the transfer to B with that to F. The absolute rec- 
ords represent a saving of 43.3 and 17.6 trials respectively, while 
the corresponding percentage records are 77.08 and 63.01. 



TRANSFER OF TRAINING AND RETROACTION 27 

The dependence of the amount saved upon the original learn- 
ing records of the second maze, is also proven by the fact that 
a positive correlation obtains between the two sets of data. The 
discussion of this correlation phenomenon will be reserved for 
the succeeding topic. 

4. A positive correlation exists between the degree of trans- 
fer and the difficulty of the second problem. 

In the preceding topic, it was maintained that the variations 
in the amounts saved is in part a function of the second activity. 
In supporting this statement, we offered as evidence the fact 
that the differences in saving are correlated with the relative 
difficulty of the second problem. We have computed the correla- 
tion between the degree of transfer and the difficulty of the 
second maze, between the amount of effort saved due to transfer 
and the amount of effort expended in the original learning. The 
materials for this correlation are easily obtained from Table i. 
The correlations were computed by the ranking method, and 
Table 3 presents the results for trials, errors, and time. 

Table 3. Correlation Between Degree of Transfer and Difficulty of 

Second Maze. 
Trials Errors Time 

Rats 1. 00 .70 .70 

Humans .50 i.oo i.oo 

A positive correlation obtains in the table by all three of the 
criteria and for both humans and animals. With the rats a per- 
fect correlation exists for trials, and plus .70 for errors and 
time. In the human records we find a perfect correlation in 
the matter of errors and time, and a value of plus .50 by the 
criterion of trials. 

In view of the fact that these values are based upon but five 
mazes for the animals, and upon three for the humans, one 
can not credit the validity of any single value, especially those 
as low as .50. The validity of the results must depend rather 
upon their uniformity. A positive correlation was obtained in 
every one of the six cases, and this fact enhances the probability 
of the validity of any single measurement manyfold. On the 
other hand, one must not be embued with scepticism because a 



28 LOUIE WIN FIELD WEBB 

perfect correlation was not obtained in every case. Our con- 
clusion merely states that the degree of transfer depends in part 
upon the difficulty of the second maze. Subsequent records will 
prove that the transfer effect is also a function of the first maze, 
and hence a perfect correlation with the data for either of the 
two mazes is not to be expected. 

5. A positive correlation exists between the degree of trans- 
fer and the similarity of two maze patterns. 

The main difficulty in a comparison of this kind concerns the 
measurement of the degree of similarity between any pair of 
mazes. One of the current theoretical explanations of the phe- 
nomenon of transfer is stated in terms of the partial identity of 
the neural elements existing between the two activities. Any 
measurement of such a relation between two activities is neces- 
sarily impossible. 

In this experiment, we employed two methods of measuring 
the similarity of a pair of maze patterns. The first method used 
w^as that of 'order of merit' or 'relative position.' Nineteen 
individuals, who understood the maze problem, were asked to 
rank the five mazes in order as to their similarity to Maze A. 
They were asked to judge the similarity upon the basis of the 
two factors of the positional relation of the true pathway and 
the cul de sacs, and the direction of the course of travel. The 
results of these nineteen judgments were as follows: B was 
placed in first place 17 times and in second place twice; D was 
ranked second 17 times and first two times; C was given fifth 
rank by 14 and third rank by 5. The most difficult task con- 
cerned the ranking of E and F. The majority (11 out of 18), 
however, gave F the preference. From these judgments the 
mazes were ranked as follows: B-i, D-2, F-3, E-4, and C-5. 
The rankings as to the degree of transfer were determined from 
Table i. 

The results of the computations are given in Table 4. It will 
be noted that the correlation is positive by each of the criteria 
for both humans and rats. As regards trials there is the result 
of plus .30 for the rats and plus .50 for the humans. The record 
by errors gives a correlation of plus .70 for rats and i.oo for 



TRANSFER OF TRAINING AND RETROACTION 29 

Table 4. Correlation Between Amount Saved in Transfer and 

Similarity of Mazes. 

Trials Errors Time 

Similarity by Order of Merit. 

Rats .30 .70 .60 

Humans .50 1. 00 i.oo 

Similarity in Terms of Diflficulty of Mastery. 

Rats .70 .90 .30 

Humans .50 .50 i.oo 

humans; in the time records the rats have a correlation of .60 
and the humans i.oo. Some of the values are high enough to 
indicate a valid correlation. Other values are so low that little 
importance can be attached to their significance when regarded 
singly. The validity of the results must depend primarily, not 
upon individual instances, but upon their uniformity. Some de- 
gree of positive correlation obtains for all six measurements, and 
this fact enhances their probable significance manyfold. 

The second method measured the similarity of a pair of mazes 
in terms of their relative difficulty of mastery. If Maze A re- 
quired forty trials for its mastery, while Mazes B and C were 
mastered in thirty and fifteen trials respectively, it is evident 
that A and B are more similar in respect to difficulty than are A 
and C. The five pairs of mazes can thus be ranked as to relative 
difficulty in terms of trials, errors, and time from the compara- 
tive data of Table i. 

These correlations are also given in Table 4, and a positive 
value again obtains for the six comparisons. The validity of 
these correlations again depends upon their uniformity. 

We also compared the ranking as to similarity by the first 
method with the three sets of ranks obtained by the second 
method. The correlation value for trials was minus .30, while 
positive values of .50 and .60 were obtained for errors and time 
respectively. This indicates that any judgments as to the rela- 
tive similarity of pairs of maze problems will anticipate more 
correctly their relative difficulty when measured by time and 
errors than by the factor of trials. 

6. The transfer results are somewhat similar for the human 
and animal groups. Evidently the laws and conditions governing 
transfer are not radically different in the two organisms. 



30 LOUIE WIN FIELD WEBB 

Transfer obtained for both human and animal subjects and 
its character was positive or beneficial in both cases. However, 
the rats evidenced more ability in utilizing a previous maze ex- 
perience in a new situation, which is proven by the fact that 
the rats effected a larger saving in the transfer. The difference 
is quite pronounced and obtains for each of the three pairs of 
mazes when the results are stated in either absolute or relative 
terms. This is evident from an examination of the comparative 
data of Table 5. Rats and humans differ little, however, when 
the transfer is measured by the saving of errors, but the differ- 
ence such as it is favors the human subjects. The humans ef- 
fected the greater saving of errors for two of the three pairs 
of mazes for both the absolute and relative methods of stating 
the results. Thus, on the whole, the rats were able to profit more 
from their previous tuition in Maze A when the effect is meas- 
ured in terms of trials or time. The rats expended the greater 
amount of trials and time to master A and made the greater 
saving of trials and time because of this previous training in A. 
The humans, on the other hand, required the greater number of 
errors to master A, and likewise profited the most from this 
tuition when its effects are measured in terms of errors. This 
fact will be observed by a comparison of the records for the 
original learning of Maze A as given in Table 5. This differ- 
ence between humans and animals as to the amount saved due 
to their previous experience in A would seem to be a result of 
the character of that training. In other words, the amount of 

Table 5. Comparative Results of Humans and Rats 
Absolute Amounts Saved. 





Trials 


Errors 


Time 




Rats 


Humans 


Rats Humans 


Rats 


Humans 


A— 5 


43-3 


22.8 


192.2 252.8 


2068.1 


1016.6 


A-C 


27.4 


7.5 


109.2 26.9 


1037.2 


214.6 


K—D 


II-5 


6. 
Percentage 


122.4 192. 
Amounts Saved. 


2511.1 


686.3 


h—B 


77.08 


67.86 


85.81 88.64 


83.77 


67.18 


K-€ 


57.85 


19.74 


46.10 20.20 


34.94 


28.19 


A-D 


69.02 


51.98 


79.71 9458 


90.42 


88.73 



Records for Original Learning of Maze A. 
38.9 24.3 205.9 231.2 1782.4 970.8 



TRANSFER OF TRAINING AND RETROACTION 31 

transfer would seem to be in part a function of the character of 
the training secured in the previous maze, a proposition which 
will be further demonstrated by the succeeding experiment. 
While humans and animals manifest some difference as to the 
amount saved, yet they are similar in the following respects : 
that pair of mazes which induces the greatest amount of saving 
for rats has a like effect with humans; mazes which give the 
least effect with humans produce similar results with the rats. 
This formulation is true for the transfer stated in either absolute 
or relative terms ; the truth of the proposition may be determined 
by computing the correlation between the amounts saved for the 
two classes of subjects. These correlation values were deter- 
mined separately for trials, errors, and time when stated in both 
absolute and relative terms. The rankings were secured from 
Tables i and 2 and the results are to be found in Table 6. 

Table 6. Correlation of Transfer Between Humans and Animals. 

Trials Errors Time 

Absolute 1. 00 1. 00 .50 

Relative i.oo .50 i.oo 

It is observed from the above table that there is a perfect 
correlation for trials in both absolute and relative terms; for 
errors we have a perfect correlation in absolute terms and plus 
.50 in relative terms; for time the results are i.oo in relative 
terms and plus .50 in absolute terms. Thus we observe that in 
six cases of comparison there are four perfect correlations, and 
two of only fifty. However, we again put forth the statement 
that we must not judge by a single case, but by all the cases. 
So the consistency of the positive results strengthens the prob- 
ability of a high correlation between human and animal learning 
as regards the phenomenon of transfer. 

These facts prove not only that transfer obtains for both 
the human and animal realms, but that human and animal or- 
ganization is highly similar so far as the laws and conditions 
of transfer are concerned. It further indicates that the processes 
involved are highly similar, and that no factors, such as rational 
activities peculiar to the human subjects, are functioning in this 
process of transfer. 



32 LOUIE W INFIELD WEBB 

7. A positive correlation exists between any two of the three 
criteria of measurement. 

The efficiency of the criteria used in measuring any part of 
the learning process, is a question of great importance. In meas- 
uring the transfer effect in this study we have employed three 
criteria, trials, errors, and time. The interdependent relation 
existing between any two of these criteria can best be determined 
by correlation. The correlation values were computed from the 
records of the individuals in each of the transferred groups. 
The ranking method was used, and the results are given in 

Table 7. 

Table 7. Correlation Between Criteria of Measurement. 

Rats 
Trials-Errors 1 
A—B .48 

A— C .34 

A—D .76 

A—E .83 

A—F .67 

Humans 
A—B —.10 

A—C .93 

A—D .78 

From this table of data, the following comparisons can be 
made. ( i ) The correlation is positive in twenty-three of the 
twenty-four cases. This uniformity indicates the existence of 
some dependent relation between trials and errors, trials and 
time, and errors and time as a means of measuring the transfer. 

(2) The human subjects exhibit the higher values in five of the 
nine cases of comparison. Whether this is due to chance or 
represents a general tendency, it is impossible to say at this time. 

(3) A higher correlation obtains between time and errors than 
between trials and either of the other two criteria in six of the 
eight possibilities. But apparently no difference obtains for trials 
and errors as compared with trials and time. (4) The pair of 
mazes A-D gives the highest values in five of the six cases. No 
uniform difference obtains between A-B and A-C. 



Is-Time 


Errors-Time 


•03 


.92 


• 15 


.87 


.76 


•94 


.88 


.76 


•74 


•93 


.40 


.70 


.56 


■37 


.83 


.88 



TRANSFER OF TRAINING AND RETROACTION 33 

B. Dependence of Transfer upon the Character of the 

First Problem. 

The object of the second experiment is to determine the de- 
pendence of the degree of transfer upon the nature of the first 
maze. 

The possibiHty of the degree of transfer depending upon either 
the first or second learned problem has been previously men- 
tioned. This was illustrated from the discussion about the 
Classics. The student may learn mathematics, history and sci- 
ence first and then study Latin; the degree of transfer in this 
instance might depend, not upon Latin, but upon the previously 
mastered subject. This is the type of problem to be discussed 
in this section of our paper. 

In order to test experimentally such a proposition as was raised 
in the perceding paragraph, one factor must be kept constant. 
Maze A is again the constant activity. One group of subjects 
first learned Maze B and then was transferred to Maze A. An- 
other group was transferred from C to A, one from D to A, 
a fourth from E to A, and a fifth from F to A. The varying 
factor in this situation is the first learned maze; the second 
acquired problem is kept constant for all of the groups. If the 
degree of transfer is wholly a function of the second or constant 
activity, the variations should be only such as can be accounted 
for in terms of group, or mere chance differences. Should 
marked variations obtain in the degree of transfer, it can be said 
that these are due in part to the differences in the character of 
the first learned problem. 

The amount of transfer was measured in the manner described 
in the preceding topic, viz., by the comparison of the transferred 
learning with the original mastery of the same maze. A control 
group for Maze A is therefore necessary, and this group con- 
tained 54 rats and 21 humans. The computations were figured 
in the same manner as described above for the three criteria 
of trials, errors, and time. 

Table 8 presents the results in the absolute terms of group 
averages. These group averages, together with the average 
deviations, for the original and the transferred learning are 



34 LOUIE JVINFIELD WEBB 

Table 8. Comparative Records of Original and Transferred Learning. 

Rats 





Trials 


Errors 


Time 


A 


38.9±i2.9 


205.9± 60.9 


I782.4±82i.8 


B—A 


7.7± 6.6 


97± 9-5 


22I.3±2I2.5 


Sav. 


31.2 


196.2 


I561.I 


C-A 


i9-3± 8.9 


76.3 ± 28.6 


487.1 ±218.6 


Sav. 


19.6 


129.6 


1295-3 


D—A 


23.7±ii.7 


58.8± 39.2 


457. ±1997 


Sav. 


152 


147.1 


13254 


E—A 


22.5±11.6 


82.3± 36.8 


65i.5±3i8. 


Sav. 


16.4 


123.6 


1 130.9 


F—A 


35.1 ±10.9 


99.2± 24.9 


704.7±254.4 


Sav. 


3.8 


106.7 
Humans 


10777 


A 


24-3 ± 9-7 


23I.2±III.6 


970.8±388.2 


B—A 


5- ± 4.8 


5-84: 57 


ii8.6±i04.7 


Sav. 


19-3 


225.4 


852.2 


C-A 


25.5± 8.1 


i7i.7±io6.3 


67o.2±38o.8 


Sav. 


— 1.2 


59-5 


300.6 


D—A 


27.5±io. 


I28.5± 57-1 


524.3± 153.8 


Sav. 


—3-2 


102.7 


446.S 



given for each of the criteria. The letters in the table indicate 
the records for the several mazes; thus A denotes the record 
for the original learning of that maze, and B-A indicates the 
transferred learning of the same maze. The B. C, D, E, F in 
connection with A, e. g. C-A etc., means that the previous maze 
experience of the group consisted of the maze shown by that 
letter. The symbol Sav. refers to the average amount saved for 
each group and these figures thus measure the transfer effect 
for each group. 

From an examination of the data in this table, we are able 
to make the following conclusions, which will be illustrated and 
discussed in order. 

I. The nature of the transfer is positive for all five mazes. 
The above statement is true for twenty-two of the twenty-four 



TRANSFER OF TRAINING AND RETROACTION 35 

instances of comparison. The two instances that failed to show 
positive transfer are found in the human records for trials in 
the transfer from C-A and T)-A, and yet in these two cases a 
positive transfer obtains in terms of errors and time. In the 
transfer from C to A a loss of practically 5% is noted by the 
criterion of trials, and in the transfer from D to A, by the same 
criterion, a loss of over 13% is observed. The cause of this is 
not known ; it may represent a matter of chance, or it may be 
a valid instance of negative transfer. In the transfer from C 
to A the loss is rather small, and a saving of over 40% is shown 
by the other two criteria, and this fact might argue that chance 
is responsible. One consideration may be offered, which tends 
to indicate that this loss is due to an individual peculiarity. In 
this transferred group, T)-A, one subject used more trials to 
learn Maze A than did the other twenty-one subjects. This same 
person was also the most erratic subject in the original learning 
of Maze D; he used next to the largest number of trials, made 
considerably more errors, and consumed much more time than 
did any of the other subjects. The average deviation for his 
group in the transferred record T>-A is larger than in the original 
learning of A, and this fact, we believe, can be attributed to this 
individual's record. Judging from these considerations, it ap- 
pears to us that the results prove, with a high probability, that 
positive transfer exists in the cases C-A and T>-A with human 
subjects. 

The three possible causes for the differences between the rec- 
ords of the original and the transferred learning, that were sug- 
gested in discussing topic A, are equally relevant here. The 
causal factors may be chance, group differences, or the previous 
training of the transferred groups. The arguments pre- 
viously advanced to prove that the differences are real and 
represent a transfer effect have an equal bearing in this con- 
nection. It is noted that the average deviations are rather wide, 
and this result is due perhaps to the small number of subjects 
in the various groups. For the data of this table we computed 
the Probable Difference, and in twenty-one of the twenty-four 
instances of measurement the actual dift'erence is found to ex- 



36 LOUIE WINFIELD IV EBB 

ceed the probable difference. We have the same situation as 
regards the matter of consistency; the differences are uniformly 
lower for the transferred records in twenty-one of the twenty- 
four instances of measurement. This consistency strengthens 
the probability, to a high degree, that chance is not responsible 
for the differences. The groups used in this experiment were 
secured and mixed as described in the previous experiment, thus 
eliminating the possibility of the differences being due to group 
variations. Further the control group is composed of a rather 
large number of subjects. Every subject that originally learned 
Maze A during the eight months of the experimentation was 
utilized in this control group. This fact lessens to a greater 
degree the possibility that group differences are functioning in 
any large part. We have thus shown by mathematical calculation 
and by the matter of consistency, that chance can not be func- 
tioning to a significant degree; the possibility of group diff'er- 
ences being a large causal factor is eliminated by our method 
of securing and mixing the subjects of the various groups. 
Hence, we again believe, beyond doubt, that the nature of the 
transfer is positive. 

In this, as in the former experiment, the transfer effect re- 
mained positive, despite our efforts to so arrange the maze pat- 
terns in such a way as to produce a negative effect. These 
relations between the maze patterns have been described and 
illustrated. The transfer from C to A reverses the direction of 
travel; D and A involve a new arrangement of cul de sacs. 
E and A represent a transfer from a simple to a difficult pat- 
tern, while F to A involves an increase in the length of the true 
pathway and a new arrangement of cul de sacs. 

2. The degree of transfer in this experiment is in part a 
function of the first problem. 

As we have previously stated, the second maze is the constant 
activity, while the first maze is different for each pair. If the 
degree of transfer is a function of the constant factor, the differ- 
ences should not vary beyond what can reasonably be attributed 
to mere chance. On the other hand, if the degree of transfer 
varies beyond the possibility of mere chance differences, this re- 



TRANSFER OF TRAINING AND RETROACTION 37 

suit must be regarded as a function of the first or varying 
activity. 

By an inspection of Table 8, it will be observed that the amount 
saved in absolute terms varies considerably in the five cases with 
the rats and in the three cases with the human subjects. The 
records of the rats vary by trials from 3.8 to 31.2, and those 
of the humans from — 3.2 to 19.3. For errors rats have a range 
in the saving varying from 106.7 to 196.2, and the humans from 
59.5 to 225.4. In the time records there exist equally wide 
variations; those of the rats vary from 1077.7 to 1561.1, and 
those of the humans from 300.6 to 852.2. 

The previous discussion (page 24) of the significance of such 
wide variations in the degree of transfer is in point here. We 
believe that the possibilities are rather remote that mere chance 
would cause such a wide range of variations as noted. By com- 
paring the amounts saved (Table 7) with the figures represent- 
ing the original mastery of the five mazes (Table i), it will be 
noted that the two sets of data are roughly proportionate. For 
example, the largest saving in trials for the rats was obtained 
in the transfer from B and this maze required the greatest num- 
ber of trials for its mastery. Likewise C mediated the next 
highest amount of saving in trials and this maze was also second 
as to difficulty of mastery. The dependence of the amount saved 
in each case upon the difficulty of the first maze is best demon- 
strated by computing the correlation between the two sets of 
data. By referring to the correlation values in Table 9 below, 
it is observed that a positive correlation exists for trials, errors, 
and time, and for both humans and rats. This fact proves that 
as changes in the character of the first maze were made, corre- 
sponding changes in the degree of transfer occurred. Hence, 
we believe that we are justified in concluding that the varying 
degree in the transfer effect is in part a function of the varying 
activity, viz. the first learned problem. 

3. A positive correlation is found to exist between the degree 
of transfer and the difficulty of the first problem. 

The values of Table 9 represent the correlation between the 
amounts saved in the transfer to iMaze A and the amounts of 



38 LOUIE WINFIELD WEBB 

effort, figured by trials, errors, and time, expended in the original 
mastery of Mazes B, C, D, E, and F. The ranking method of 
computation was employed. 

Table 9. Correlation Between Degree of Transfer and Difficulty of 

First Problem. 

Trials Errors Time 

Rats .60 .60 .50 

Humans .90 i.oo i.oo 

On examining Table 9, it is noted that the correlations are 
positive in every instance for both humans and rats. The data 
between which the correlation was computed in each case were 
so few in number that but little reliance can be placed upon the 
validity of any one of the correlation values. In estimating the 
validity of these values, the uniformity of positive results must 
be emphasized. A positive correlation was secured in each of 
the six comparisons, and this consistency increases the prob- 
ability of any single value manyfold. The validity of the values 
can not be attacked because a perfect correlation was not ob- 
tained in each case, for such is not to be expected as we demon- 
strated in our first experiment, that the amount of transfer is 
also correlated with the difficulty of the second of each pair 
of mazes. 

The correlation values are noticeably higher for the human 
subjects than for the rats. It is hardly possible to determine 
whether this difference is due to chance, or to some difference 
between human and animal organisms. 

4. A positive correlation is found between the amount of 
transfer and the degree of similarity of the two maze patterns. 

Table 10. Correlation Between Amount Saved in Transfer and 

Similarity of Mazes. 

Trials Errors Time 

Similarity by Order of Merit. 

Rats .10 .60 .60 

Humans .50 i.oo i.oo 

Similarity in Terms of Difficulty of Mastery. 

Rats .10 .80 .00 

Humans .50 .50 i.oo 

The degree of similarity between any two maze patterns was 



TRANSFER OF TRAINING AND RETROACTION 29 

measured by the same two methods as were used in the first 
experiment. In fact the rankings as to similarity are the same 
in both experiments. The correlation values are given in 
Table lo. 

A positive value was secured in ii of the 12 comparisons, 
and these positive values range from .10 to i.oo. The validity 
of our conclusion must again depend upon the uniformity of the 
results. The values are higher for the humans in five of the 
six cases, and in general errors and time give higher values than 
does the criterion of trials. Since the rankings as to similarity 
are the same as in the first experiment, we may repeat the former 
statement that some degree of positive correlation obtains be- 
tween the two methods of estimating the similarity. 

5. A comparison of human and rat results reveals an essen- 
tial similarity. No radical difference can be inferred from these 
data. 

Both classes of subjects exhibit a positive transfer. Two ex- 
ceptions are to be found in the human records, but these are 
probably due to chance or individual peculiarity. In this ex- 
periment the rats exhibited the greater amount of transfer in 
eight of the nine instances of comparison. The single exception 
refers to the saving in errors due to the transfer from Maze B 
to A. When the amount saved is stated in terms of its per- 
centage relation to the records representing the mastery of the 
first maze, the rats again manifest the greater effect from their 
previous tuition in seven of the nine comparisons. While the 
rats were able to utilize their previous training to a greater de- 
gree than the humans, yet that maze which gave the highest 
transfer for the rats also yielded the highest value for the 
humans. On the other hand the low-est values for both humans 
and rats were secured from the same maze. A perfect positive 
correlation obtained for each of the three criteria, and when the 
transfer is stated in both absolute and relative terms. 

6. The results indicate a positive correlation between any 
two of the three criteria of measurement. 

As in the previous instance of determining such a correlation, 
we have computed the values from the records of the individuals 



40 LOUIE IVINFIELD WEBB 

in each of the transferred groups. The ranking method of cor- 
relation was employed, and Table ii presents the results upon 
which the above conclusion is made. 

Comparisons, such as were made in the first experiment, can 
also be made from the data in this table. ( i ) There is a positive 
value in all of the twenty-four cases, and this again indicates 
the existence of some dependent relation between any two of 
the three criteria as a means of measuring the transfer. (2) The 
human subjects exhibit higher values in eight of the nine com- 
parisons. We are unable at this point to determine whether 
this is due to chance, or whether a general tendency is present: 
(3) Little uniformity obtains as to the matter of higher values 
between errors and time and either of the other two criteria. 
Likewise, there is a lack of uniformity in comparing the results 
for trials and errors, and trials and time. (4) No definite state- 
ment can be made as to uniformly higher values for any one pair 
of mazes. 

Table ii. Correlation Between Criteria of Measurement. 





Rats 








Trials-Errors 


Trials-Time 


Errors-Time 


B—A 


.78 


.98 


.80 


C—A 


.61 


.67 


•75 


D—A 


•97 


•97 


•93 


E—A 


•95 


•55 


.62 


F—A 


.48 


.88 


.29 




Humans 




B—A 


1. 00 


1.00 


1. 00 


C—A 


.83 


.83 


I. GO 


D—A 


•99 


.90 


•95 



C. Dependence of Amount Saved upon Direction of 

Transfer. 

The purpose of this section is to determine whether or not 
the amount saved is in part a function of the direction of trans- 
fer between any pair of mazes. 

The problem is readily stated in terms of mazes. In one case 
the transfer is from A to B, while a second group is transferred 
from B to A. The same pair of mazes is employed in both tests; 
the experiments differ only in what we have termed the direction 



TRANSFER OF TRAINING AND RETROACTION 41 

of the transfer. If the amount saved is different for the two 
cases, the direction of the transfer must account for the result. 
If the direction of transfer is not a determining factor, the de- 
gree of saving should be practically the same for both experi- 
ments. 

No new experimental data are required for the solution of 
this problem, as the first experiment furnishes the results from 
groups that were transferred from Maze A to each of the other 
five mazes, while the second experiment gives us the data for 
the opposite direction of transfer for the same pairs of maze 
problems. The results from the two previous experiments, found 
in Tables i, 2, 7, and 8, are thus utilized and the data so ar- 
ranged in Tables 12 and 13 as to facilitate a comparison of the 
amounts saved for the two directions of transfer. Separate 
comparisons are made for the human and rat subjects, for each 
of the five pairs of mazes, and for each of the three criteria of 
measurement. Table 12 states the amounts saved due to transfer 
in absolute terms, while in Table 13 a comparison is made of 
the saving stated in relative or percentage terms. The symbol 
A-B means that the subjects were transferred from A to B, while 
B-A refers to the opposite direction of transfer for the same 
pair of mazes. The symbol Dif. indicates the difference in the 
amounts saved in the two directions of transfer. 

I. The direction of transfer is in part a deciding factor in 
determining the degree of transfer. 

The differences between the two sets of results may be due 
to group peculiarities, chance, or the direction of transfer. The 
possible functioning of group peculiarities has been obviated by 
our method of group selection. While differences exist for all 
tvv'enty-four cases of comparison, yet such a result would nat- 
urally be expected even though chance were the only factor 
operating. Neither are the differences in the majority of the 
cases large enough to exclude the possibility of chance. The 
influence of the direction of transfer in mediating the differ- 
ential results is proven by the fact that the differences are a 
function of the degree of similarity of the various pairs of 
mazes. That pair of mazes possessing Ihe highest degree of 



42 LOUIE IVINFIELD WEBB 

similarity yields the smallest difference of saving when the direc- 
tion of transfer is reversed, while the largest difference of saving 
tends to obtain for the most dissimilar pair of mazes. The size 
of the differences for the various pairs of mazes is thus not 
entirely a matter of chance; it depends to a slight extent upon 
the degree of similarity of the maze patterns. To prove this 
relationship, we have computed the correlation between the size 
of the differences and the degrees of similarity of the various 
pairs of mazes. From the data of Table 12, we ranked the pairs 
in the order of increasing values of differential results, and 
correlated this order with those representing their degree of 

Table 12. Comparative Amount Saved for Two Directions of Transfer. 

Rats 





Trials 


Errors 


Time 


A—B 


43-3 


192.2 


2068.1 


B—A 


31.2 


196.2 


1561.1 


Dif. 


12.1 


4.0 


507.0 


A—C 


27.4 


109.2 


1037-2 


C—A 


19.6 


129.6 


1295-3 


Dif. 


7.8 


20.4 


258.1 


A—D 


"•5 


122.4 


2511.1 


D—A 


152 


147. 1 


1325-4 


Dif. 


37 


24.7 


1 185.7 


A—E 


■9 


10.4 


135-4 


E—A 


16.4 


123.6 


1130.9 


Dif. 


15-5 


113-2 


995-5 


A— F 


17.6 


54-7 


719- 1 


F—A 


3-8 


106.7 


1077-7 


Dif. 


13.8 

Humans 


52.0 


358.6 


A—B 


22.8 


252.8 


1016.6 


B—A 


193 


225.4 


852.2 


Dif. 


3-5 


27.4 


164.4 


A—C 


7.5 


26.9 


214.9 


C—A 


—1.2 


59-5 


300.6 


Dif. 


8.7 


32.6 


85.7 


A—D 


6.0 


192.0 


686.3 


D—A 


—3-2 


102.7 


446-3 


Dif. 


9.2 


89.3 


239-8 



TRANSFER OF TRAINING AND RETROACTION 43 

similarity as determined by the two methods described in the first 
experiment — similarity of difficulty, and similarity of maze pat- 
terns. For the rat records, positive values of .30, i.oo, and .20 
were secured for trials, errors, and time, respectively when the de- 
gree of similarity was measured in terms of difficulty of mastery. 

Table 13. Comparative Percentages Saved for Two Directions of Transfer. 





Rats 








Trials 


Errors 


Time 


A—B 


77.08 


85.81 


83-77 


B—A 


80.11 


95-27 


87-58 


Dif. 


303 


9.46 


3.81 


A— C 


57.85 


46.10 


34-94 


C-A 


50.38 


62.94 


72.67 


Dif. 


747 


16.84 


37-73 


A—D 


69.02 


79-71 


90.42 


D—A 


39-14 


71-43 


74-36 


Dif. 


29.88 


8.28 


16.06 


A— £ 


19.91 


54-63 


63.40 


E—A 


42.12 


60.03 


63-44 


Dif. 


22.21 


5-40 


.04 


A— F 


63.01 


42.78 


59.44 


F—A 


9-59 


51.81 


60.46 


Dif. 


53-42 

Humans 


9-03 


1.02 


A—B 


67.86 


88.64 


87.18 


B—A 


79.41 


97-49 


87.78 


Dif. 


11.35 


8.85 


.60 


A—C 


19.74 


20.20 


29.18 


C—A 


-4-98 


25-74 


30.97 


Dif. 


24.72 


5-54 


1.79 


A—D 


51-98 


94-58 


88.73 


D—A 


—13.21 


44-42 


45-99 


Dif. 


65-19 


50.16 


42.74 



The corresponding values for the human subjects were .50, — .50, 
and — .50. The mazes were also ranked as to differential results 
by taking an average of the values for the three criteria, and 
correlation values of .67 and .50 were secured for the rat and 
human subjects respectively. The differential results were also 



44 LOUIE IVINFIELD WEBB 

correlated with the degree of similarity determined by the method 
of the 'order of merit/ and the following values were obtained: 
rats, .20, .40, and — .10 for trials, errors, and time respectively; 
the corresponding values for humans were .50, .50, and — .50; 
when the order of differential results was determined by averag- 
ing the values for the three criteria, values of .10 and .50 were 
secured for the rats and humans respectively. The mazes were 
again ranked in order of increasing values of the differential 
results as given in percentage terms in Table 13. This system 
of values was likewise correlated with the degree of similarity 
of the maze patterns. These correlation values were practically 
identical with those above and so need not be given. It is noted 
that small positive values predominate; positive values were se- 
cured in 14 of the 17 computations. The validity of our proposi- 
tion must depend upon the consistency with which these positive 
values were secured. To our mind these data prove that the 
direction of the transfer between any pair of mazes exerts some 
slight effect upon the resulting degree of saving. 

2. The relative amount of retracing differs according to the 
direction of transfer. 

The data supporting this conclusion are found in Table 14. 
W^e recorded separately the errors due to entrances into cul de 
sacs, and returns over the true path. The table gives in per- 
centage terms the number of retracing errors relative to the 
total number of errors made in the mastering of each maze. For 
example, in the mastery of B by the rats, 41.7% of the total 
number of errors was due to retracing. The corresponding value 
f-or the transferred learning of B is 60.77^- In this case the 
transfer increased the relative amount of retracing, and this 
fact is denoted in the table by the positive sign plus placed after 
the value 60.7%. A different result was obtained for the op- 
posite direction of transfer. The percentage values are 40.3 
and 27.8 respectively for the original and the transferred mastery 
of A. Transfer in the direction of B-A thus decreased the rela- 
tive number of errors due to retracing, and this fact is indicated 
in the table by the minus sign placed after the value 27.8. 
Direction of transfer thus operates differently for the mazes A 



B 65.8 
A-B 59.8— 


A 69.3 
B-A 27.6— 


C 48.4 
A-C 44.2 — 


A 69.3 
C-A 69.6+ 


D 60.3 
A-D 60.9+ 


A 69.3 
D-A 64.S— 



TRANSFER OF TRAINING AND RETROACTION 45 

and B; one direction increases the relative amount of retracing 
while the other increases it. An inspection of the positive and 
minus signs for the various pairs of mazes reveals the fact that 
this differential effect due to the direction of transfer obtains 
for four of the five comparisons of rat records and for two of 
the three cases for the human subjects. 

Table 14. Percentage of Errors Due to Retracing. 

Rats Humans 

B 41.7 A 40.3 

A-B 60.7+ B-A 27.8— 

C 66.7 A 40.3 

A-C 76.3+ C-A 38.3— 

D 71.5 A 40.3 

A-D 75.3+ D-A 17.2— 

E 54.7 A 40.3 

A-E 41.8— E-A 36.1— 

F 33.7 A 40.3 

A-F 35.1+ F-A 30.1— 

3. The influence of the direction of the transfer is essentially 
identical for human and animal subjects. 

The correlation values given above (page 43 f.) are essentially 
similar for the two types of subjects. It will be noted in Table 12 
that the direction B-A gives for both humans and rats a smaller 
saving in trials than does the reverse direction of A-B. In six 
of the nine possible comparisons of this sort, those directions 
giving the greater saving for the rats also give the larger values 
for the human subjects. This correlation is perfect when the per- 
centage values of Table 13 are utilized in the comparison. Evi- 
dently the conditions governing transfer are essentially the same 
for the two types of organism. 

D. Locus OF THE Transfer in the Learning Curve. 

Our purpose here is to compare the original and transferred 
learning curves, thus enabling us to discover what part of the 
learning curve is affected by the transfer. 

Transfer reduces the total amount of time and the total num- 
ber of errors in learning a maze. This reduction may be accom- 



46 LOUIE WIN FIELD WEBB 

plished in one of three ways, (i) The saving may be distributed 
proportionately among the various trials. In this case the curves 
for the transferred and the original learning would be similar 
in form but different only in height. For example, the number 
of errors made in each trial in transfer may be one half of that 
made in the original mastery of the same maze. (2) The two 
curves may be identical in height and form for the first trials and 
differ only in the final trials. In this case the saving due to trans- 
fer would be confined to the final stages of mastery, and the curve 
for the transferred learning would exhibit a sudden final drop. 
(3) The saving due to transfer may also be confined to the early 
trials. In this instance, the curve for the transfer would begin 
with much lower values than the curve for the original mastery, 
decrease much more gradually at first, and finally become iden- 
tical with that for original learning in the last stages of mastery. 
The initial drop characteristic of the normal maze curve would 
thus be absent in the transfer curve. The term 'locus of transfer' 
will be used to represent that group of trials in which the transfer 
effect is mainly manifested. 

The locus of transfer is on the average confined to the first 
five trials. Subjects transferred to any maze are saved the 
equivalent of the first five trials of effort; they begin the problem 
at an advanced stage of mastery and complete it in a normal 
manner. The transferred curves thus do not exhibit that sharp 
initial drop characteristic of normal curves. 

This general conclusion is illustrated by typical data found 
in Figures 7 and 8. To the left of each figure are found the 
error and time curves representing the progress of learning for 
the first five trials of the original mastery of the various mazes. 
To the right is placed the initial part of the corresponding curves 
for transferred learning. It will be noted that the transferred 
curves begin at a level closely approximating that reached by 
the curves for the original learning at the fifth trial. These 
particular curves have been selected for purposes of illustration, 
because they represent not only the average but the most frequent 
in the sixteen cases of comparison. Twelve of the sixteen cases 
closely approximate the conditions represented by these figures. 



TRANSFER OF TRAINING AND RETROACTION 47 



SO 



40 




MUMAMS 



/A-B 



12 3^5 




I E 3 4. 5 



50 




48 



LOUIE W INFIELD WEBB 




RaT6 



P-A 




* — . 




Rats 



D-A 



FIGURE a 



TRANSFER OF TRAINING AND RETROACTION 49 

Four cases diverge from the type. In C-x\ for the humans and 
A-F for the rats, the two curves are more nearly identical in 
form. B-A and A-D for the humans represent the opposite di- 
vergence from the type; here the saving due to transfer is equiva- 
lent to seven or eight trials. 

E. Selective Effect of Transfer upon Types of Error. 

Transfer effects a saving in the total number of errors neces- 
sary to master a maze. These errors comprise two sorts — those 
due to entering cul de sacs, and those due to retracing in the true 
pathway. We have listed these two types of error separately, 
and have computed the degree of saving for each. This was 
done by dividing the number of errors made in the original mas- 
tery of the maze into the number occurring in the transfer; this 
quotient was then subtracted from one hundred. These per- 
centage values are found in Table 15. For example the transfer 
from A to B reduced the number of retracing errors by 79.4%, 
and the cul de sac errors by 90.4%. Transfer in this case was 
more efficacious upon the cul de sac errors than upon those due 
to retracing. The purpose of this section is to determine whether 
transfer has a greater effect upon one type of error than upon 
the other. 

Transfer on the whole exerts a slightly greater effect upon 
retracing. It tends to minimize the tendency to retrace relatively 
more than it does the tendency to enter cul de sacs. 

The above conclusion is evident from an inspection of the data 
in Table 15. The percentage values are larger in 11 of the 16 
cases of comparison. There is no essential difference betv^'een 
humans and animals as to the selective effect. Nor does the 
differential effect depend upon the direction of the transfer. 
Transfer is more effective upon retracing in some pairs of mazes 
than in others, but this difference of effect with the various pairs 
of mazes is not correlated with their similarity; neither is it 
correlated with the difficulty of the mazes measured by the 
number of errors involved in either original or transferred 
learning. 



50 LOUIE WINFIELD WEBB 

Table 15. Giving the Percentage of Decrease Due to Transfer in Num- 
ber OF Retracing and Cul de Sac Errors Respectively. 
Rats 
R^ 
A-B 
A-C 
A-D 
A-E 
A-F 

B-A 
C-A 
D-A 
E-A 
F-A 



A-B 
A-C 
A-D 

B-A 
C-A 
D-A 

In those mazes in which the greatest saving of cul de sac errors 
is exhibited, transfer also tends to give the greatest saving in 
retracing. 

The evidence to support this conclusion was determined by 
correlating the two sets of values given in Table 15. The re- 
sults were .60 and .90 for the rats, and i.oo and i.oo for the 
humans. These correlation values mean that in measuring the 
degree of transfer between various pairs of mazes, one can utilize 
the saving in retracing, or the saving in cul de sac errors, or the 
saving in the total number of errors, as we have done, without 
materially changing the results. 

F. Summary. 

Upon the basis of the foregoing study of transfer, we have 
been able to make the following conclusions. 

I. The nature of the transfer is positive. The learning of 
one maze has a beneficial effect in the mastery of a subsequent 
maze situation. We tested the nature of the transfer for both 



racing 


Cul de sac 


794 


90.4 


38.0 


61.5 


78.8 


82.2 


654 


41.9 


40.2 


450 


96.8 


94.3 


64.9 


61.7 


87.9 


60.4 


643 


57-2 


63.8 


43.8 


imans 




89.7 


86.7 


28.9 


II-5 


96.1 


87.0 


99.1 


94.1 


25-5 


26.3 


48.7 


36.2 



TRANSFER OF TRAINING AND RETROACTION 51 

directions between five pairs of mazes with rats, and three pairs 
with human subjects. We thus secured sixteen separate tests 
of the nature of the transfer. In all of the sixteen cases the 
result was positive. We also used three criteria of measurement 
— trials, errors, time — thereby obtaining 48 separate measure- 
ments of the transfer. In 46 of these measurements the average 
for the test group was smaller than that for the control group, 
thus indicating a positive transfer. It might be argued that the 
difference between the original and transferred learning records 
was due to chance or group differences. That the differences 
were not due to chance, but to the positive transfer, was proven 
by the fact that the actual difference was found to exceed the 
probable difference in 45 of the 48 comparisons. Further, the 
consistency with which the differences occurred lessened the 
probability manyfold of chance being a primary causal factor. 
Our method of securing the subjects and of selecting the groups 
eliminated the probability of group differences functioning to a 
significant degree. Hence we conclude that the primary causal 
factor determining the differences between the original and trans- 
ferred learning records is not chance or group differences, but 
the positive nature of the transfer. 

In the 48 measurements of the transfer two exceptions oc- 
curred to the positive results. These were found with the human 
subjects by the criterion of trials. In these two instances we have 
shown that the loss was probably due to an individual peculiarity. 
Furthermore, in these two cases the transfer as measured by 
errors and time was of a strong positive character. While we 
admit the possibility that these two exceptions were caused by 
negative transfer, we believe that the greater probability favors 
the transfer being of a positive nature, and that we are justified 
in concluding that the transfer was positive in the sixteen tests. 

The transfer remained positive despite our efforts to produce 
conditions that would give a negative result. In the first pair of 
mazes, A and B, the construction was so designed as to give 
a high degree of positive transfer, and the results verified our 
expectations. The purpose in designing the other four pairs of 
mazes was the desire to secure conditions that would produce 



52 LOUIE W INFIELD WEBB 

a negative effect, and in every instance we were disappointed in 
the outcome. We do not conclude that it is impossible to demon- 
strate a negative transfer effect between two pairs of mazes. On 
the contrary, we admit such a possibility. However, for the 
conditions maintained in this experiment, the transfer was of a 
positive nature. 

2. Transfer is a composite process consisting of both positive 
and negative elements, and the total result is determined by the 
predominance of the one or the other of these elements. The 
total effect was positive although the presence of a negative ele- 
ment w^as shown to exist. ]\Iaze F was designed in relation to 
Maze A in such a manner that it was possible for us to deter- 
mine whether certain habits acquired in A exerted a negative 
effect in the subsequent mastery of F. Subjects with the Maze A 
experience had greater difficulty in eliminating the tendency to 
enter section 6-10 in F, entered this section much more fre- 
quently, and made many more errors in this section, than did 
those subjects without such an experience. This evidence, we 
believe, proves the existence of a negative element in the trans- 
ferred learning of Maze F. In order to produce a negative trans- 
fer effect, conditions will have to be arranged wherein the 
negative element predominates. 

3. The degree of transfer is determined by a number of 
factors. 

(i) It is in part a function of the nature of the second activ- 
ity. The first activity w^as constant for all of the groups in the 
first experiment, while the second problem varied with each 
group. The divergence of the results was wide enough to indi- 
cate that the activity set up in the second maze situation was in 
part a causal factor. The proof to substantiate this conclusion 
was found in the fact that the relative amounts saved in the five 
cases was correlated with the relative difficulty of the second 
mazes as measured by the original records of mastery. A posi- 
tive correlation w^as found in all six cases of comparison. 

(2) The activities acquired in the first problem determine in 
part the degree of the transfer. In this instance the second maze 
was constant, and the varying activity was the first problem. 



TRANSFER OF TRAINING AND RETROACTION 53 

This conclusion was proven by the fact that the amounts saved 
and the original learning records were roughly proportionate, 
and by the consistency of the positive values found in determining 
the correlation between the degree of transfer and the difficulty 
of the first problem. 

(3) The degree of transfer is dependent in part upon the de- 
gree of similarity of two maze patterns. The evidence for this 
conclusion was determined by computing the correlation between 
the degree of transfer the similarity of the five pairs of mazes. 
Two methods were utilized in securing these correlation values — 
the order of merit, and difficulty of mastery. This gave twelve 
values for each experiment. In the first case all twelve values 
were positive, while in the second 11 of the 12 values were posi- 
tive. The significant thing here was the consistency with which 
positive values occurred. This fact enhanced their validity 
manyfold, and, we believe, amply justified the above conclusion. 

(4) The amount saved is determined in part by the direction 
of the transfer. Differences were found to exist for the opposite 
directions of transfer, stated in both absolute and relative terms. 
The influence of the direction of transfer in mediating the dif- 
ferential results was proven by the fact that the differences are 
a function of the degree of similarity of the various pairs of 
mazes. That pair of mazes most similar yielded the smallest 
difference of saving when the direction of transfer was reversed, 
while the largest difference of saving tended to obtain for the 
most dissimilar pair of mazes. This relationship was tested by 
computing the correlation between the size of the differences 
and the similarity of tlie various pairs of mazes. Seventeen 
values were obtained, and 14 of these were positive. We believe, 
that the consistency with which positive values occurred proves 
the above conclusion. 

4. The laws and conditions of transfer are essentially iden- 
tical for the two types of organism employed in this study. 

The transfer was positive for both human and rat subjects. 
This was the result in the six cases of comparison when the maze 
patterns were identical, and the conditions of experimentation 
highly similar. The results were the same for the two types 



54 LOUIE W INFIELD WEBB 

of subjects in two respects. First : That pair of mazes which 
induced the greatest amount of saving for the rats had a like 
effect with human subjects; mazes which gave the least results 
with the human subjects produced a similar effect with the rats. 
This comparison was proven by determining the correlation 
values in absolute and relative terms. Of the nine values result- 
ing seven were perfect and two were plus fifty. Second : The 
influence of the direction of the transfer was essentially identical 
for humans and rats. That direction which gave the greater 
saving for the rats also gave the larger values for the human 
subjects in six of the nine possible comparisons. When the cor- 
relations were computed in relative terms all of the values were 
perfect. While the total result was similar for rat and human 
subjects, there was one difference noted. The rats evidenced 
more ability in utilizing a previous maze experience in a new 
situation than did the human subjects. The difference favored 
the rats to a pronounced degree in all three pairs of mazes in 
both experiments when measured by trials and time, and whether 
stated in relative or absolute terms. Measured by the criterion 
of errors, the human subjects manifested the greater saving. 
A possible explanation of the differences was offered in the char- 
acter of the previous training. Upon the total evidence, we con- 
cluded that human and animal organization are highly similar 
so far as the laws and conditions of transfer are concerned; 
that the processes involved were highly similar, and that no 
factors, such as rational activities peculiar to the human subjects, 
were functioning in the process of transfer. 

5. A positive correlation was found between any two of the 
three criteria of measurement. There were 24 values in each 
experiment; in the first 23 of these were positive, and in the 
second all were positive. This indicates that some dependent 
relation exists between trials and errors, trials and time, and 
errors and time as a means of measuring the transfer. In the 
first experiment higher values predominated between time and 
errors, but in the second experiment there was little uniformity 
as to higher values. This lack of uniformity prevented us from 
drawing any conclusion as to the greater validity of any two 
of the three criteria of measurement. 



TRANSFER OF TRAINING AND RETROACTION 55 

6. The locus of transfer was on the average confined to the 
first five trials. The subjects were saved the equivalent of the 
first five trials of effort. Twelve of the sixteen comparisons 
approximated the average. The exceptions ranged in the amount 
saved from two to eight trials. This means that in the trans- 
ferred learning the subjects attacked the new problem at an ad- 
vanced stage, varying from the second to the eighth trial, and 
completed the mastery in a normal manner. 

7. Transfer exerted some selective effect upon the types of 
error. The tendency to retrace the true pathway is minimized 
relatively more than the tendency to enter cul de sacs. This 
conclusion was supported by the fact that when the reduction in 
the two types of error was stated in relative terms, the values 
representing retracing were larger in 11 of the 16 cases of com- 
parison. This differential effect does not seem to depend upon 
the direction of the transfer, the difficulty of the mazes, nor upon 
the degree of similarity of a pair of mazes. These facts indicate 
that the selective effect upon retracing represents some general 
transfer effect applicable to all maze conditions. 

It was further proven that that pair of mazes which produced 
the greatest or the least effect upon retracing had a similar effect 
upon cul de sacs. This was determined by correlating the two 
sets of data, and high positive values resulted in every case. This 
means that the general effect of the transfer was the same for 
both types of error; that pair of mazes which gave the greatest 
reduction in retrace errors also produced the greatest effect upon 
cul de sac errors, but the effect was greater upon retracing. Thus 
we concluded that one could utilize the saving in retracing, cul 
de sac errors, or both without materially changing the results. 

G. Theoretical Discussion. 

It is not our purpose to formulate a theory of transfer. We 
shall confine our discussion to a consideration of two of the 
prevalent theories in relation to our results. 

Bagley^ maintains that transfer depends upon the development 
of ideals. Habits of neatness acquired in one school subject 

1 W. C. Bagley, The Educative Process, p. 208. 



56 LOUIE WINFIELD WEBB 

will transfer to other school subjects only in so far as an ideal of 
neatness has been inculcated. An ideal in this sense implies some 
sort of ideational purpose, and to my mind the theory indicates 
the doctrine that transfer can occur only on an ideational level. 
This negative aspect of the theory is controverted by the data 
of this paper. Our facts prove rather conclusively that a high 
degree of positive transfer can occur on a purely sensori-motor 
level. Transfer was manifested by the rats, and it is generally 
presumed that such organisms do not possess ideational powers. 
Furthermore, the rats exhibited a greater degree of positive 
transfer than did the human subjects. If transfer is mediated 
only by ideational activities, we are forced to assume that human 
beings are inferior to rats in intellectual capacity, at least so far 
as the maze situation is concerned. That ideals were not an 
effective factor in our experiments is proven by the fact none 
of the human subjects were previously aware that they were 
to be transferred from one maze to another, while many of the 
subjects remained in entire ignorance of the fact that a new 
maze problem had been substituted in the course of the experi- 
ment. 

Thorndike's theory" postulates that transfer occurs between 
two activities only when these activities possess identical neural 
elements or bonds of connection, and that the degree of transfer 
is proportional to the degree of identity of the bonds. This 
theory, as first stated, would not permit the existence of any 
negative transfer effect. The existence of negative transfer has 
been demonstrated by several experiments, and our results further 
prove that the total transfer effect between any complex set of 
activities is a composite affair consisting of both positive and 
negative elements. Poffenberger^ in a recent Columbia study, 
with the probable approval of Thorndike, has modified the theory 
so as to logically include the negative factor. He states that 
transfer occurs when there is at least a partial identity of bonds. 
When the bonds established in the first activity are broken in 
the acquisition of the second act, negative transfer results. When 

- Thorndike ; op. cit. 

3 Poffenberger : The Influence of Improvement in One Single Mental 
Process upon Other Related Processes. Jr. Ed. Psych. Vol. 6. 



TRANSFER OF TRAINING AND RETROACTION 57 

the bonds remain unbroken and are utilized in the second activity, 
positive results are secured. This theory possesses a great deal 
of a priori plausibility. Our conclusion that the degree of trans- 
fer is in part a function of the degree of similarity of the two 
maze patterns would seem on first thought to confirm this theory. 
Our conclusion that the degree of transfer is dependent to some 
extent upon the direction of transfer would likewise militate 
against the theory, for logically the partial identity of neural 
bonds possessed by two sets of activities should be independent 
of their temporal order. However, we wish to maintain that 
neither of the above conclusions can be regarded as constituting 
either a refutation or a confirmation of the theory. It would 
be rather ridiculous to assert that any two sensori-motor activities 
must possess a degree of neural identity proportionate to the 
relative amount of effort expended in their acquisition. The- 
oretically one might accjuire two activities totally isolated in the 
nervous system whose acquisition involved equal amounts of ef- 
fort. Objective similarity of maze patterns does not necessarily 
mean a subjective similarity of the neural activities involved in 
their mastery. To my mind, herein lies the weakness of the 
Thorndike theory. Its validity can never be adequately tested. 
Any general agreement as to the degree of neural identity be- 
tween any two complex problems is impossible. One can explain 
any fact of transfer on this basis, for all that is necessary is to 
assume the appropriate relationship between the nervous activ- 
ities, and naturally it is practically impossible to disprove this 
particular assumption. Any theory or any explanation of the 
laws of transfer should possess some diagnostic value. One 
should be able to predict to some extent the degree of transfer 
to be obtained between any two activities. Thorndike's theory 
is defective in this respect. 

Our facts indicate that transfer is to a large extent a function 
of the particular relationship existing between the two activities. 
A determination of the laws and conditions of this phenomenon 
must involve a thorough and complete analysis and definition 
of the essential relations obtaining between any two activities. 
This suggests that such complex activities as are involved in 



58 LOUIE WJNFIELD WEBB 

the mastery of a maze situation constitute a poor medium for 
any comprehensive analysis of transfer. Experiments must be 
devised by the results of which we will be able to diagnose the 
relations between the two activities ; such as keeping the reactions 
similar but varying the stimulus, or keeping the stimulus constant 
and varying the reactiojis. The problem is to simplify the situa- 
tion and isolate and control the elements so as to ultimately 
analyze the existing relationships. 



III. RETROACTION 

A. Retroactive Effect of a Certain Activity upon 
Various Other Activities. 

The first experiment concerns the retroactive effect which the 
mastery of Maze A may exert upon the retention of Mazes B, 
C, D, E, or F. The questions at issue are the existence and 
nature of retroaction and its dependence upon the character of 
the habit affected. Two groups of subjects, a test and a control 
group, are necessary for each of the five pairs of mazes. In the 
test experiment, each of five groups of subjects learns one of 
the mazes B, C, D, E, and F; all are then transferred to Maze A; 
after thirty days mainly devoted to the mastery of A, each group 
is required to relearn its first maze. This procedure may be rep- 
resented by the symbol B-A-B. In the control experiment, five 
groups are utilized and they repeat the above procedure with 
the exception of the mastery of Maze A; the symbol B — B thus 
represents the progression of events. The records secured in 
relearning Maze B in the test experiment represent the disintegra- 
tion of the Maze B habits due to the thirty day interval plus the 
retroactive effect of the acquisition of A. The relearning records 
in the control experiment, however, represent merely the dis- 
integration resulting from the thirty day interval. Any retro- 
active effect of A on B is thus measured by the difference in the 
amount of effort expended by the two groups in relearning B. 

The test group on Maze B comprised 12 rats and 5 humans, 
while the control group consisted of 8 rats and 5 humans. On 
Maze C, both the test and the control group had 9 rats and 5 
humans. The test group for Maze D consisted of 7 rats and 6 
humans, and the control group had 6 rats and 5 humans. There 
were 9 and 7 rats respectively in the test and control groups for 
Maze E. The test group for Maze F consisted of 8 rats, and 
the control group of 7 rats. 



6o 



LOUIE WIN FIELD WEBB 



Table i6. The Retroactive Effect of A upon B. 









B-A-B 




Rats 








B 


B 








Trials 


Errors 


Time 




Trials 


Errors 


Time 


Subj. 


L. 


R. 


L. 


R. 


L. 


R. 


Subj. 


L. 


R. 


L. 


R. 


L. 


R. 


I. 


23 


3 


7i 


5 


916 


55 


I. 


2>Z 





113 





1 174 





2. 


58 


I 


460 


I 


12650 


71 


■2, 


49 





189 





1211 





3- 


94 


4 


409 


6 


7404 


80 


3- 


53 


23 


205 


17 


1532 


388 


4- 


40 





265 





2708 





4- 


43 


8 


128 


9 


1347 


135 


5- 


69 





238 





2126 





5- 


7Z 





304 





2106 





6. 


35 





96 





1 124 





6. 


51 


12 


204 


22> 


1449 


211 


7. 


49 


30 


234 


37 


1430 


419 


7- 


59 


12 


198 


9 


1059 


164 


8. 


44 


43 


191 


48 


1241 


606 


8. 


48 





155 





990 





9- 


104 


8 


353 


7 


3204 


142 
















ID. 


45 


II 


209 


12 


1998 


179 
















II. 


67 


3 


232 


I 


1764 


57 
















12. 


88 


39 


224 


36 


1940 


526 




























Humans 














I. 


53 


II 


250 


14 


1669 


322 


I. 


Zl 


3 


1003 


13 


1791 


62 


2. 


30 





190 





903 





2. 


66 





591 





1780 





3- 


20 


15 


64 


27 


720 


211 


3- 


6 





36 





598 





4- 


29 





235 





740 





4- 


9 


2 


116 


3 


500 


29 


5. 


35 


10 


80 


10 


964 


175 


5- 


50 





287 





1995 






Table 17. Retroactive Effect of A upon C. 









C-A-C 




Rats 








C 


C 








Trials 


Errors 


Time 




Trials 


Errors 


Time 


Subj. 


L. 


R. 


L. 


R. 


L. 


R. 


Subj. 


L. 


R. 


L. 


R. 


L. 


R. 


I. 


30 


I 


414 


71 


12567 


696 


I. 


78 





167 





1364 





2. 


57 





202 





1189 





2. 


78 


I 


286 


7 


2223 


48 


3- 


35 


I 


188 


I 


1 192 


17 


3- 


78 





246 





2083 





4- 


36 


3 


177 


7 


1234 


36 


4- 


78 





281 





1638 





5- 


74 





250 





1604 





5- 


78 


I 


329 


I 


4304 


31 


6. 


58 


3 


475 


8 


3210 


48 


6. 


46 


2 


175 


23 


6815 


166 


7- 


12 


2 


169 


2 


264 


26 


7- 


74 





221 





1647 





8. 


36 





202 





1041 





8. 


71 





205 





1907 





9- 


48 





167 





1310 




Huma 


9- 

NS 


86 


3 


308 


12 


2502 


128 


I. 


19 


27 


99 


201 


627 


7Z7 


I. 


25 


12 


174 


10 


774 


114 


2. 


Z7 


4 


38 


7 


762 


59 


2. 


25 





121 





. 864 





3- 


46 





208 





691 





3. 


48 


12 


188 


13 


479 


13 


4- 


40 





72, 





574 





4- 


67 


3 


147 


I 


792 


13 


5- 


43 


8 


171 


6 


1 1 10 


89 


5- 


30 


5 


119 


7 


692 


65 



TRANSFER OF TRAINING AND RETROACTION 



6i 



Table i8. Retroactive Effect of A upox D. 









D-A-D 




Rats 








D 


D 








Trials 


Errors 


Time 




Trials 


Errors 


Time 


3Ub. 


. L. 


R. 


L. 


R. 


L. 


R. 


Subj. 


L. 


R. 


L. 


R. 


L. 


R. 


I. 


13 





145 





2943 





I. 


7 





130 





1193 





2. 


23 


6 


122 


5 


1521 


93 


2. 


19 


3 


91 


7 


4094 


108 


3- 


8 





203 





3335 





3- 


38 


3 


144 


5 


1550 


59 


4- 


31 


I 


164 


I 


1912 


24 


4- 


12 


5 


73 


30 


1155 


309 


5- 


25 


3 


394 


25 


8668 


109 


5- 


II 


I 


175 


5 


3617 


51 


6. 


10 


4 


109 


18 


2563 


153 


6. 


II 





163 





1953 





7. 


9 





84 





1601 































Humans 














I. 


13 


15 


84 


S2, 


600 


380 


I. 


12 





180 





1158 





2. 


i8 


31 


207 


59 


928 


293 


2. 


3 


4 


67 


23 


416 


328 


3- 


15 


12 


207 


9 


854 


III 


3- 


3 





5 





70 





4- 


7 


3 


37 


5 


235 


50 


4- 


5 


4 


90 


3 


466 


51 


5- 


19 


6 


1113 


17 


2764 


53 


5- 


31 





202 





903 





6. 


2 


7 


41 


20 


115 


90 

















Table 19. Retroactive Effect of A upon E. 



E-A-E 



Rats 





Trials 


Errors 


Time 




Tria 


Is 


Errc 


rs 


Time 


Subj. 


L. 


R. 


L. 


R. 


L. 


R. 


Subj. 


L. 


R. 


L. 


R. 


L. R. 


I. 


3 


7 


17 


7 


202 


74 


I. 


8 





36 





277 


2, 


6 


6 


26 


II 


377 


104 


2. 


I 





14 





105 


3. 


6 





34 





262 





3- 


6 





6 





yi-2 


4- 


I 





19 





125 





4- 


3 





7 





208 


5- 


II 





31 





135 





5- 


2 


4 


7 


5 


178 50 


6. 


5 





19 





121 





6. 


I 


4 


14 


2 


127 26 


7. 


8 


3 


18 


8 


349 


2,6 


7- 


5 





20 





221 


8. 


2 


2 


15 


3 


105 


28 














9- 


2 


I 


21 


2 


279 


22 















Table 20. Retroactive Effect of A upon F. 



F-A-F 



Rats 





Trials 


Errors 


Time 




Trials 


Errors 


Time 


Subj. 


L. 


R. 


L. R. 


L. R. 


Subj. 


L. R. 


L. 


R. 


L. R. 


I. 


14 


16 


70 58 


491 278 


I. 


17 I 


86 


10 


816 27 


2. 


32 





84 


591 


2. 


21 5 


163 


9 


I 179 48 


3- 


23 


25 


159 177 


1009 1499 


3- 


7 4 


64 


5 


1688 27 


4- 


39 


3 


165 6 


1090 38 


4- 


12 12 


81 


21 


692 152 


5- 


35 


7 


186 86 


1145 573 


5- 


30 5 


115 


28 


909 135 


6. 


50 


14 


178 96 


I 37 I 704 


6. 


38 4 


146 


16 


927 215 


7- 


39 


20 


139 103 


iioi 420 


7- 


34 13 


105 


16 


1456 120 


8. 


28 


26 


186 51 


3682 346 













62 LOUIE IVINFIELD WEBB 

The individual relearning records for the test and control 
groups and for each of the mazes are given in Tables 1 6 to 20 
in the columns marked R. The differences between the two 
series of relearning records may be due to chance, group peculiar- 
ities, or retroaction. The possibility of group peculiarities being 
a large causal factor, as in the transfer experiment, has been 
obviated by our method of group selection. Any decision be- 
tween chance and a retroactive effect presents difficulty because 
of the high degree of individual variability in the relearning 
records. Hence for the present we shall refrain from making 
any conclusions regarding retroaction and content ourselves with 
mere factual statements concerning the dift'erences between the 
records of the two groups. 

1. The occurrence of any disintegrating effect due to time, 
or to time and retroaction combined, is an individual matter. 

Some individuals were affected and some w^ere not susceptible 
to the influences. Individual exemptions were present in 14 of 
the 16 groups of subjects. Out of 82 rats, 31 were not affected, 
and II of the 31 human subjects manifested no disturbance. Of 
the total number of subjects employed in the experiment 2>7% 
suffered no disturbing effect. The human and animal subjects 
manifested no difference as to their immunity. If retroaction is 
present, its operations are certainly confined to specific in- 
dividuals. 

2. The individual variability in the relearning records is much 
greater than in the original mastery of the same maze. 

For the purposes of this comparison we have inserted in Tables 
16 to 20 the individual records for the original learning of the 
various mazes. These are found in the columns marked L. The 
values under L and R thus give the individual learning and re- 
learning records respectively of the various subjects. The valid- 
ity of our proposition is apparent from an inspection of these 
data. We computed, however, for each group the averages and 
the average deviations for the learning and relearning records. 
Each average deviation is divided by the corresponding average, 
thus expressing the value of the deviation relative to the average 
in percentage terms. These various percentile values are given 



TRANSFER OF TRAINING AND RETROACTION 63 

in Table 21. The columns L and R give the values for learning 
and relearning respectively. It is to be noted that the relative 

Table 21. Individual Variability in Learning and Relearning. 

Rats 

Test Groups Control Groups 

Trials Errors Time Trials Errors Time 

Group L R L R L R Group L R L R L R 

B-A-B 34 107 33 108 71 95 B — B 16 100 22 100 19 100 

C-A-C 34 93 29 136 89 146 C — C 9 no 19 149 45 141 

D-A-D 47 100 41 118 49 102 D — D 39 83 24 94 48 92 

E-A-E 52 loi 24 loi 36 97 E — E 60 143 50 133 27 142 

F-A-F 25 57 26 58 46 68 F— F 42 55 26 40 27 56 

Humans 

B-A-B 26 84 45 81 27 80 B — B 62 120 77 122 46 120 

C-A-C 17 113 44 157 22 133 C— C 39 70 16 73 15 70 

D-A-D 42 58 91 78 53 71 D — D 80 120 60 136 57 133 

variability in relearning is the greater in each of the 48 compari- 
sons. On the average the relearning values are at least three 
times as large as those representing the original learning. 

There is no consistent difference as to relearning variability 
between the human and rat subjects, nor between the control and 
test experiments. Comparing the variability of mazes, there is 
but one uniform result of whose validity we may be confident. 
Maze F gives by far the lowest relearning variability values for 
all three criteria and for both the test and control groups. 

3. There is practically no correlation between the learning 
and the relearning records. 

We ranked the individuals of each group according to their 
ability in learning as measured by each of the criteria. The 
same individuals were also ranked as to their ability manifested 
in relearning the same maze, and the correlation values between 
the two sets of data were computed. These values are to be 
found in Table 22. All of the values are extremely small, and 
but 28 of the 48 values are positive. If any tendency towards 
a positive correlation be present, it is slight in amount. No 
significant differences differentiate humans from rats, the control 
and test groups, nor one maze from another. 



64 



LOUIE IVINFIELD WEBB 



Table 22. Correlation Between Learning and Relearning. 





Rats 






Test Groups 




Group 


Trials 


Errors 


Time 


B-A-B 


•30 


— .10 


—•03 


C-A-C 


—•35 


•44 


•48 


D-A-D 


•50 


.36 


.22 


E-A-E 


.06 


—■33 


•55 


F-A-F 


—■37 


.08 


■41 




Control 


Groups 




B— B 


.40 


•39 


■37 


C— C 


.33 


■37 


•85 


D— D 


.78 


—•57 


—.07 


E— E 


•05 


.04 


—.17 


F— F 


—.14 


.16 


-.46 




Humans 






Test Groups 




B-A-B 


— OS 


—■32 


•38 


C-A-C 


—■25 


—.42 


•03 


D-A-D 


.26 


.26 


■ 15 




Control 


Groups 




B— B 


— .10 


•50 


.00 


C— C 


.08 


•70 


—.60 


D— D 


— .22 


— .20 


—.40 



This general result means that individuals making good records 
in mastering a maze are just as liable as not to do poorly in 
relearning the same maze. It is thus impossible to predict from 
the learning records the relative ability of a group of subjects 
in again mastering the same maze. The individual differences 
in the relearning tests thus do not represent any permanent dif- 
ferences of individual capacity, nor are they the result of any 
habits acquired during the original mastery of the maze. The 
greater individual variability manifested in relearning as op- 
posed to learning (see former section) must thus be due, not to 
permanent individual peculiarities nor to acquired habits, but 
to individual differences in susceptibility to the disintegrating 
influences of intervening conditions. Since the relearning varia- 
bility of the control group is not greater than that of the test 
group, it is evident that time and not any possible retroactive 
effect is primarily the responsible intervening factor. 

4. A greater percentage of the subjects in the test series mani- 



TRANSFER OF TRAINING AND RETROACTION 65 

fested some degree of disintegration of the old habit. This 
greater effect may be due to retroaction. 

This generalization is apparent from the data as tabulated 
in Table 23. Of the total number of rats used in the test series, 
66.7% were disturbed while but 57% were affected in the control 
series. For the humans the percentages affected are 75 and 53.3 
for the test and control series respectively. More rats were af- 
fected in the test series for 3 of the 5 mazes, and the same state- 
ment is applicable to the humans for 2 of the 3 mazes. On the 
whole there is a uniform tendency towards a greater susceptibility 
in the test series. 

Table 23. Percentage of Subjects Affected. 







Rats 


Hum 


lans 


Group 


Test 


Control 


Test 


Contr( 


B 


75-0 


50.0 


60.0 


40.0 


C 


55-5 


44-4 


60.0 


80.0 


D 


57-0 


66.7 


lOO.O 


40.0 


E 


55-5 


28.S 






F 


87.5 


lOO.O 






Total 


66.7 


57-0 


750 


53-3 



5. The average amount of disintegration for those subjects 
aft"ected is on the whole somewhat higher in the test series. 

The comparative data supporting the above generalization are 
to be found in Table 24. For the rats the test series gives the 
higher values in 13 of the 15 cases of comparison. With the 
humans higher values are found in the test series in all 9 in- 
stances of comparison. Considering the values for rats and for 
humans as single groups, the test series gives the higher values 
for all three criteria of measurement. The rat values in the 
test series are the larger in 3 of the 5 mazes, while the human 
values are higher for all three mazes. In the rat records the 
differences in favor of the test series are the most pronounced 
for Maze F. On the whole the humans show more evidence of 
negative retroaction than do the rats. 

6. The percentage of disintegration or loss during the thirty 
day interval is on the whole somewhat higher in the test series. 

Table 25 presents the comparative data in support of the above 
statement. The test series in the rat records gives the higher 



66 LOUIE WIN FIELD WEBB 

Table 24. Average Relearning Records for Subjects Manifesting 
Disintegration. 

Rats 







Test 






Control 




Group 


Trials 


Errors 


Time 


Group 


Trials 


Errors 


Time 


B 


1578 


17.00 


237.22 


B 


13.50 


1450 


224.50 


C 


2.00 


17.80 


164.60 


C 


1.75 


10.75 


93.25 


D 


3.50 


12.25 


94.75 


D 


3.00 


11.75 


131.75 


E 


3.80 


6.20 


52.80 


E 


4.00 


3.50 


38.00 


F 


15.85 


82.12 


552.00 


F 


7.14 


15.00 


102.85 


Average 


8.18 


27.07 


220.27 




5.88 


II. 10 


118.07 








Humans 








B 


12.00 


17.00 


236.00 


B 


2.50 


8.00 


45-50 


C 


1300 


71-33 


295.00 


C 


8.00 


7.75 


63.75 


D 


12.33 


27.17 


162.83 


D 


4.00 


12.50 


37.90 


Average 


12.44 


38.50 


231.27 




4.83 


7.41 


4905 


values 


in 12 ( 


of the 15 


cases of 


comparison, and 


in the human 


records higher values are found 


in all 


nine cases 


. Look: 


ing at 



the values for the rats as a single group, as shown by the averages 
in the table, the test series gives the higher values for 2 of the 3 
criteria, while for the humans all three values are higher in the 
test series. For 3 of the 5 mazes the rat values are larger in 
the test series, while all three mazes give higher values for the 
humans. Maze D gives the greatest evidence of negative retro- 
action with humans, but with the rats this same maze shows 
more evidence of positive retroaction. Maze F in the rat records 
gives the greatest evidence in favor of negative retroaction. As 
was found in absolute terms, so also we find in relative terms 
that the humans manifest a larger disturbing effect of a retro- 
active character. 

7. An analysis of the types of error gives evidence of a greater 
disturbing effect in the test groups. 

Pechstein^ has shown in his maze experiments that subjects 
learn the maze in about the same number of trials when retracing 
is prevented as when this type of activity is allowed. Retracing 
thus plays but little part in the mastery of a maze so far as the 
number of trials is concerned. It thus follows that the retracing 
present in the learning of a maze is an incidental and useless 

1 Pcchstein. Op. cit. 



TRANSFER OF TRAINING AND RETROACTION 



67 





Table 


25. Average Percentage of '. 


Loss. 










Rats 












Test 






Control 




Group 


Trials 


Errors 


Time 


Trials 


Errors 


Time 


B 


20.8 


6.3 


10.2 


13-2 


2-7 


8.2 


C 


4.0 


2.8 


2.4 


I.I 


30 


I.I 


D 


II-5 


4.0 


2.0 


12.7 


9-3 


5.8 


E 


57-9 


17.5 


12.2 


85.0 


12.4 


7.0 


F 


50.2 


49-9 


44-6 


36.2 


13-5 


11.4 


Average 


28.85 


16.10 


14.28 
Humans 


29.64 


8.38 


6.70 


B 


25.0 


12.2 


132 


6.0 


0.8 


2.0 


C 


340 


45.0 


26.6 


19.0 


3.8 


7.8 


D 


132.0 


27-5 


35-5 


42.6 


7-2 


18.0 


Average 


6333 


28.23 


25.10 


22.53 


3-93 


9.26 



result of a peculiarity which manifests itself when an organism 
is in novel surroundings, or when it becomes lost or disturbed. 
The amount of retracing will in a measure represent the degree 
of disturbance due to novel conditions. 

As a matter of fact, retracing was much more prevalent in 
the test experiments. Table 26 gives the data for the average 
number of retrace errors in the relearning of subjects manifest- 
ing a disturbance. The rats show a larger average number of 
retrace errors in the test group in all five cases of comparison, 
while in the human records the test group gives the higher aver- 
ages in 2 of the 3 comparisons. Considering the rats and hu- 
mans as single groups, we find that the test series has a greater 
number of retraces. 



Table 26. Average of Retrace Errors in the Relearning of Subjects 
Showing a Disturbing Effect. 







Rats 


H; 


umans 


Group 


Test 


Control 


Test 


Control 


B 


0.66 


0.0 


4.0 


6.0 


C 


14.60 


9.0 


50.3 


1.2 


D 


10.00 


8.0 


14.0 


8.2 


E 


2.60 


1-5 






F 


26.30 


4.1 






Average 


10.83 


4-52 


22.76 


5.13 



Thus there appears to be a general tendency for more retracing 
to occur in the test series, which fact may argue for the presence 
of a disturbing or retroactive effect. • 



68 LOUIE W INF I ELD WEBB 

8. Certain peculiarities of behavior indicate a negative retro- 
active effect for Maze F. 

By comparing the diagrams of Mazes A and F (Figs, i and 
6), it is seen that the section numbered 6 to lo as a cul de sac 
in Maze F, corresponds to an open section in Maze A, through 
which the rat must pass in his learning of this maze. After hav- 
ing mastered F, this additional route has to be added to his maze 
experience when transferred to Maze A; while in the relearning 
of Maze F this newly acquired habit must be again omitted. 
These conditions make it possible to determine in a fairly accurate 
manner whether or not the Maze A experience is functioning 
in the relearning of F. If the rats persist in entering the section 
6-IO, it is evident that the Maze A habit is functioning in such 
a manner as to interfere in again mastering F. 

The record of the number of entrances into this section was 
kept for each subject. Rat A entered this section in 17 of his 
22 trials; rat C, 13 out of 25 trials; rat E, 7 out of 7 trials; 
rat F, 8 out of 11 trials; rat G, 12 out of 20 trials; rat H, 4 out 
of 26 trials; while rats B and D made no entrances. The record 
for the control group is quite different. Five of the rats in this 
group entered this section only one time ; one rat entered it twice, 
and one entered it three times. By this comparison, it appears 
that with the majority of the subjects in this group, the Maze A 
habit functioned in such a manner as to interfere in the relearn- 
ing of Maze F. 

9. The test series manifests the greater degree of imperfection 
of the maze habit on the first day's test. 

Previously we have measured the degree of the imperfection 
of the habit by the time necessary to relearn the maze. This has 
been termed the relearning method. The usual method of meas- 
uring the imperfection of a habit in the experiments on retro- 
action is that of recall. In a maze experiment the nearest 
approach to the method of recall is to utilize the records of the 
activity of the first day in the relearning tests as a measure of 
the imperfection of the habit. We have made such a comparison, 
and the results are given in Table 27. 



TRANSFER OF TRAINING AND RETROACTION 69 





Table 27. 


First Day 


's Activity in 


Relearning. 








Test 




Rats 




Control 




Errors 




Time 






Errors 


Time 


B-A-B 


1-9 




46.8 




B— B 


0.75 


370 


C-A-C 


9-4 




1 132 




C— C 


5-3 


61.7 


D-A-D 


2& 




61.4 




D— D 


2.8 


62.8 


E-A-E 


2.2 




22.3 




E— E 


I.O 


195 


F-A-F 


234 




154-6 
797 




F— F 


8.8 


47.8 


Av. 


7.9 


Av. 


2,-7 


45-7 








H 


UMANS 








B-A-B 


1.2 




31.6 




B— B 


2.2 


46.5 


C-A-C 


8.0 




31.8 




C— C 


1.0 


17.8 


D-A-D 


7-7 




22.S 




D— D 


Z-2 


57-4 



Av. 5.6 31.9 Av. 2.1 40.6 

On examining the data in this table, we find that with the rats 
the test group has the larger number of errors and the greater 
amount of time for four of the five mazes, while the human re- 
sults give the larger number of errors in two of the three com- 
parisons and the greater amoimt of time in one of the three 
cases. Considering all of the rats and humans as two separate 
groups, we notice that the average for the rats is larger for the 
test group for both errors and time, while for the humans the 
test group has the larger record only for errors. With rats 
31% of the subjects in the test groups were perfect in the initial 
trials, while in the control groups only 30% gave perfect records. 
In the human control groups 53% of the subjects manifested 
no disturbance in the trials of the first day, while only 24% of 
the subjects in the test groups gave evidence of no loss. Thus 
there appears to be a general tendency for the test series to 
manifest a greater degree of imperfection on the first day of 
the relearning activity. 

B. Retroactive Effect of Various Activities upon the 

Same Process. 

Our second experiment deals with the retroactive effect which 
Mazes B, C, D, E, and F may exert upon the retention of Maze 
A. The same questions are at issue, as in the previous experi- 
ment, and records from test and control groups are necessary to 



70 LOUIE W INFIELD WEBB 

determine these issues. Several groups of subjects mastered 
Maze A; one of these groups then learned Maze B, another 
Maze C, a third Maze D, one Maze E, and a fifth group was 
transferred to Maze F. After an interval of thirty days each 
group relearned Maze A. Another group mastered A and waited 
an equal length of time and relearned the same maze; this is the 
control group. The groups learning another maze in the interval 
are the test groups. The difference between the results from 
the test groups and the control groups is termed the retroactive 
effect of the second maze upon the retention of Maze A. 

The control group for rats was composed of ii subjects, and 
in the human control group there were 6 subjects. The test 
groups to determine the retroactive effect of B upon A consisted 
of 9 rats and 5 humans; to show the effect of C upon A 9 rats 
and 6 humans were used; in the test groups for D there were 
6 rats and 3 humans ; 8 rats comprised the test group for Maze E. 
The records from 9 rats are employed to determine the effect of 
F upon A. 

The relearning records for all individuals in both the test and 
control groups are found in Tables 28 and 29. The symbols 
A-B-^, A-C-A, etc., and A — A indicate the test groups and con- 
trol group respectively. Chance, retroaction, or group peculiar- 
ities may have caused the difference between the records of the 
two groups. The selection of the groups prevented group pe- 
culiarities from functioning sufficiently to cause the differences. 
Again we are confronted with such wide individual differences 
that we are unable to make any accurate judgment between 
chance and retroaction. In this section we shall also confine our- 
selves to dealing with the factual comparisons. 

I. Any disintegration due to time, or time plus retroaction, 
is an individual matter. 

Many individuals were affected and some manifested no dis- 
turbance in the tests for retention. Exemptions from the in- 
fluences are found in 8 of the 10 groups of subjects. Thirteen 
out of 52 rats, and 6 out of 19 humans gave evidence of no dis- 
turbing effect. Of the total number of subjects employed only 
73-3% were affected by time or time plus retroaction. Thus we 



TRANSFER OF TRAINING AND RETROACTION 



71 



Table 28. Retroactive Effect of Various Mazes upon A. 









A-B-A 




Rats 






A-C-A 








Trials 


Errors 


Time 




Trials 


Errors 


Time 


Subj 


L. 


R. 


L. 


R. 


L. 


R. 


Subj. 


L. 


R. 


L. 


R. 


L. 


R. 


I. 


40 


8 


191 


21 


2009 


146 


I. 


18 


I 


138 


3 


1254 


62 


2. 


43 


2 


231 


3 


3260 


31 


2. 


25 





160 





751 





3- 


20 


2 


224 


7 


4874 


189 


3- 


59 


I 


318 


52 


3176 


595 


4- 


30 


16 


194 


Z?> 


1601 


428 


4- 


45 





29s 





899 





5- 


47 


2 


270 


7 


4907 


41 


5- 


28 


6 


199 


II 


1087 


129 


6. 


48 





173 





1388 





6. 


52 


3 


254 


62 


1786 


605 


7- 


34 


I 


177 


20 


1452 


58 


7. 


14 





109 





2187 





8. 


40 





250 





2210 





8. 


30 


II 


216 


10 


872 


162 


9- 


49 





166 





1353 





9- 


42 


5 


246 


II 


1419 


149 








A-D-A 












A-E-A 






I. 


76 


2 


299 


2 


2128 


46 


I. 


35 


4 


150 


3 


2195 


60 


2. 


31 


12 


184 


27 


1 180 


188 


2. 


47 


3 


162 


5 


2708 


49 


3- 


27 


7 


144 


10 


922 


84 


3- 


27 





221 





1084 





4- 


Z2> 


I 


570 


I 


5112 


25 


4- 


34 


2 


108 


I 


2166 


53 


S- 


31 





124 





1384 





5- 


48 





158 





1213 





6. 


28 


2 


126 


I 


1582 


76 


6. 


22 


7 


174 


66 


2465 


596 
















7- 


26 


2 


136 


9 


S7Z 


51 
















8. 


44 


5 


169 


4 


1526 


72 








A-F-A 












A A 






I. 


ze 


4 


170 


6 


710 


60 


I. 


7Z 


5 


293 


9 


1773 


lOI 


2. 


2,7 


2 


196 


7 


1016 


64 


2. 


68 


3 


281 


2 


2279 


54 


3- 


43 


3 


211 


3 


1307 


49 


3- 


52 


2 


242 


4 


1684 


46 


4- 


26 


ID 


143 


25 


893 


176 


4- 


27 


20 


131 


35 


797 


306 


5- 


22 





139 





498 





5- 


70 


9 


265 


7 


4602 


137 


6. 


33 


4 


169 


12 


802 


65 


6. 


43 





193 





1077 





7. 


23 


5 


172 


19 


2196 


117 


7- 


44 





230 





1227 





8. 


28 


9 


98 


20 


587 


146 


8. 


72 


9 


356 


II 


2502 


149 


9- 


23 


4 


144 


13 


616 


59 


9- 


69 





307 





2088 



















10. 


16 


8 


143 


24 


1466 


140 
















II. 


61 


I 


294 


8 


2409 


38 




Table 29. 


Retroactive 


Effect 


OF Various Mazes upon 


A. 










A-B-A 




Humans 






A-C-- 


\ 








Trials 


Errors 


Time 




Trials 


Errors 


Time 


Sub 


. L. 


R. 


L. 


R. 


L. 


R. 


Subj. 


L. 


R. 


L. 


R. 


L. 


R. 


I. 


29 


45 


135 


53 


706 


491 


I. 


32 


14 


212 


26 


1036 


144 


2. 


7 





95 





384 





2. 


24 


Z'2 


197 


75 


607 


311 


3- 


15 





83 





329 





3. 


2 


II 


48 


18 


441 


257 


4- 


22 





181 





1702 





4- 


39 


19 


318 


18 


943 


167 


5- 


23 


5 


180 


53 


510 


182 


5- 


34 


26 


157 


57 


631 


28s 
















6. 


47 


5 


152 


19 


1471 


135 








A-D-A 












A 


-A 






I. 


18 


II 


691 


14 


1851 


134 


I. 


18 





211 





IOCS 





2. 


5 


6 


442 


15 


1585 


105 


2. 


7 


4 


68 


8 


Z^2, 


61 


3- 


40 


38 


360 


71 


1385 


415 


3. 


23 


6 


2.26 


16 


1118 


no 
















4. 


49 





531 





II 57 



















5. 


21 





193 





1437 






"72 LOUIE IVINFIELD WEBB 

again make the statement that if retroaction is present, it is con- 
fined in its operation to certain individuals. 

2. In comparing the individual variability in relearning with 
that in the original mastery of the same maze, we find much 
wider variations in the relearning. 

The records for the original mastery, in addition to the re- 
learning records, are inserted in Tables 28 and 29. The column 
marked L gives the values for the original learning, and the one 
marked R presents the individual relearning records for the 
various subjects. The above generalization is obvious from an 
examination of the comparative data in this table. In order to 
facilitate the comparison, we have expressed the value of the 
average deviation in relation to the average in percentage terms. 
These percentages will be found in Table 30. The columns L 
and R give the values for learning and relearning respectively. 
For the rats the relative variability in the relearning is greater 
in all 18 cases of comparison, while in the human records there 
is a greater variability manifested in the relearning in 10 of the 
12 comparisons. On the average the relearning values are ap- 
proximately twice as large as the values for the original mastery. 

The two exceptions noted above are to be found in the human 
records; however, on the whole there is no consistent difference 
between the rat and hum.an records. The two exceptions with 
the humans may be due to the fewer number of subjects in these 
two groups. No consistent difference is apparent between the 
test and control groups, nor between the various mazes. 

Table 30. Individual Variability in Learxixg and Relearxixg. 

Rats 





Trials 


Errors 


Time 


Group 


L 


R 


L 


R 


L 


R 


A-B-A 


18 


no 


15 


97 


46 


lOI 


A-C-A 


37 


97 


29 


108 


42 


92 


A-D-A 


34 


91 


53 


114 


51 


67 


A-E-A 


23 


65 


14 


125 


37 


no 


A-F-A 


21 


50 


16 


52 


37 


52 


A— A 


29 


87 
Hu: 


22 

MAXS 


85 


36 


81 


A-B-A 


35 


140 


27 


119 


53 


72 


A-C-A 


38 


44 


25 


27 


34 


31 


A-D-A 


85 


72 


41 


75 


27 


65 


A— A 


43 


120 


46 


125 


26 


120 



TRANSFER OF TRAINING AND RETROACTION 73 

3. Our evidence fails to justify the conclusion that there is 
any correlation between the learning and the relearning records. 

As in the former instance dealing with a similar correlation, 
we ranked the individuals according to their ability as manifested 
in the learning and relearning of the same maze. The correlation 
values between these two sets of data are given in Table 31. The 
majority of the values are too small to be significant, and only 
16 of the 30 values are positive. From this it appears that there 
is no general tendency towards a positive correlation between the 
two sets of values. The differences between the humans and 
rats, the control and test groups, and the various mazes, are ap- 
parently not significant. 

Table 31. Correlation Between Learning and Relearning. 





Rats 






Test Groups 




Group 


Trials Errors 


Time 


A-B-A 


-■37 .28 


■33 


A-C-A 


.08 .56 


•42 


A-D-A 


—.31 .39 


—.60 


A-E-A 


—.21 .32 


•45 


A-F-A 


—.14 —.25 
Control Group 


.25 


A— A 


.13 —.04 
Humans 
Test Groups 


.21 


A-B-A 


.90 .38 


.40 


A-C-A 


.00 .13 


—.82 


A-D-A 


1. 00 — 1. 00 
Control Group 


—■50 


A— A 


.00 .00 


—•30 



The result in this instance strengthens the validity of our con- 
clusion in the corresponding section of the first experiment : The 
ability manifested by individuals in learning a maze is no index 
to their relative ability in relearning the same maze. Again we 
conclude that individual susceptibility to the disintegrating effects 
of time is responsible for the pronounced variability in the re- 
learning records. 

4. In the test series a greater percentage of the subjects gives 
evidence of some degree of disintegration of the old habit, than 
is found in the control series. Retroaction may be operating to 
cause this greater effect. 



74 LOUIE WIN FIELD WEBB 

The data in support of the above statement will be found in 
Table 32. There was 76.08% of the total number of rats used 
in the test series disturbed by the influences, while 72.7% were 
affected in the control series. The human records show 80% 
and 40% affected in the test and the control series respectively. 
More of the rats were affected in 3 of the 5 test groups, while 
in 2 of the 3 test groups of the humans there was a larger percent 
affected. Tavo of the human test group had 100% of the sub- 
jects affected. A greater susceptibility to the influences is ap- 
parent in the test series. 

Table 2^. Percentage of Subjects Affected. 







Rats 


Humans 


Group 


Test 


Control 


Test 


Control 


A-B-A 


66.6 


72.7 


40 


40 


A-C-A 


66.6 




100 




A-D-A 


83-3 




100 




A-E-A 


750 








A-F-A 


88.9 








Average 


76.08 


72.7 


80 


40 



5. For those subjects affected the average amount of disinte- 
gration is on the whole slightly higher in the test series. 

For evidence in support of the above statement see Table 33. 
Higher values are found in the test series for the rats in 7 of 
the 15 cases of comparison. In the human records the test series 
give higher values in all 9 instances of comparison. Looking 
at the rat and human values as single groups, higher values are 
present with rats in two of the three criteria, with humans in 
all three criteria.. No single maze in the rat records gives uni- 
formly higher values in the test series, while all three mazes do 
so for the humans. For the rats Maze D gives the greatest evi- 
dence of positive retroaction, while Maze C manifests the greatest 
amount of disturbance. In the human records Maze B gives the 
greatest evidence for negative retroaction. The results indicate 
that the humans are more susceptible to negative retroaction than 
are the rats. 

6. The disintegration or loss during the thirty day interval 
is on the whole somewhat higher in the test series when the re- 
sults are stated in percentage terms. 



TRANSFER OF TRAINING AND RETROACTION 
Table 33. Average Relearning Records for Subjects Manifesting 



75 







Disintegration. 














Rats 












Test 






Control 




Group 


Trials 


Errors 


Time 


Trials 


Errors 


Time 


A-B-A 


5-17 


15.17 


151.00 


7.09 


12.50 


121.38 


A-C-A 


450 


22.83 


263.67 








A-D-A 


4.80 


8.13 


87.20 








A-E-A 


3.83 


14.67 


146.83 








A-F-A 


5-11 


14.38 


92.00 








Average 


4.68 


15.03 


148.14 
Humans 


7.09 


12.50 


121.38 


A-B-A 


25.00 


53.00 


336.50 


5.00 


12.00 


85.50 


A-C-A 


17.83 


3550 


216.50 








A-D-A 


18.33 


33-33 


184.66 








Average 


20.39 


37-27 


245.89 


500 


12.00 


85.50 



The comparative data upon which the above generalization is 
based are given in Table 34. The human test series give higher 
values in all nine cases of comparison, while the test series in the 
rat records give higher values in 7 of the 15 comparisons. Con- 
sidering the average for the humans as a single group, higher 
values are found in the test series by all three criteria; the test 
series with the rats give higher values for 2 of the 3 criteria. 
Only Maze F gives uniformly higher values in the test series for 
the rats, and hence manifests a negative retroactive effect; Maze 
B evidences the greatest positive retroactive effect. All three 
mazes give uniformly higher results for the humans in the test 
series. The humans manifest a greater negative retroactive ef- 
fect than do the rats. 





Table 


34. Average Percentage of Lo 


ss. 










Rats 












Test 






Control 




Group 


Trials 


Errors 


Time 


Trials 


Errors 


Timi 


A-B-A 


10.5 


5-1 


4.9 


15.2 


5.4 


6.1 


A-C-A 


9-3 


6.3 


10.9 








A-D-A 


13-3 


4.2 


5.8 








A-E-A 


9-4 


6.5 


7.0 








A-F-A 


16.0 


8.3 


9.8 








Average 


11.7 


6.08 


7.68 
Humans 


15.2 


5.4 


6.1 


A-B-A 


39.0 


13.8 


21.2 


14.6 


3.8 


5.4 


A-C-A 


1390 


23.8 


32.5 








A-D-A 


92.0 


8.3 


14.7 








Average 


90.0 


15-3 


22.8 


14.6 


3.8 


5.4 



76 LOUIE WINFIELD WEBB 

7. A greater disturbing effect in the test series is evident from 
an analysis of the types of error. 

In this connection we shall consider only the subjects that 
manifested some degree of disintegration. The comparative data 
for this topic are given in Table 35. The rats have a larger 
average number of retrace errors in the test series for 4 of the 5 
mazes, and the human test series give the greater number of re- 
traces in all three mazes. Considering the humans and rats as 
single groups, the test series for each group has the larger average 
number of retraces. Granting the hypothesis that the presence 
of retrace errors is an evidence of disturbance, we have here 
some evidence in favor of a retroactive effect. 

Table 35. Average of Retrace Errors in the Relearning of Subjects 
Manifesting Disintegration. 





Rats 


Humans 


Group 


Test 


Control 


Test 


Control 


A-B-A 


10.16 


4.12 


34-50 


8.00 


A-C-A " 


18.66 




18.00 




A-D-A 


0.00 




8.66 




A-E-A 


12.66 








A-F-A 


4.87 








Average 


9.27 


4.12 


20.38 


8.00 



8. A greater degree of imperfection of the maze habit is found 
with the test series on the first day of the test for retention. 

In considering the retroactive effect in the preceding topics of 
this section, we have utilized the relearning or saving method. 
In this topic we wish to approximate the method of recall ; hence 
we shall make use of the records of the activity of the first day 
in the relearning tests. The results for both the test and control 
groups will be found in Table 36. 

By comparing the data in this table, we discover that for the 
rats the test group has the larger number of errors in four of 
the five cases of comparison, and the larger amount of time in 
three of the five cases. The test groups for the humans give 
larger values in the error column in all three comparisons, and 
for time they have the larger average in two of the three cases. 
The averages for all the members of the several test groups are 
larger than for those of the control group for the humans and 



TRANSFER OF TRAINING AND RETROACTION 77 



Table 


36. First Day's 


Activity in Relearning. 






Rats 






Test 




Control 




Errors 


Time 




Errors Time 


A-B-A 


5-2 


64.1 




A — A 4.0 47.4 


A-C-A 


12.8 


162.9 






A-D-A 


2.5 


43-2 






A-E-A 


7-6 


82.6 






A-F-A 


4-4 


37-2 
78.0 






Av. 


6.5 








Humans 




A-B-A 


10.6 


44.2 




A — A 0.4 26.2 


A-C-A 


6.8 


47-6 






A-D-A 


4.8 


24.8 







Av. 7.4 38.8 

the rats by both criteria. We believe that this evidence is suffi- 
cient to warrant the statement that there is a general tendency 
for the test groups to manifest a greater degree of imperfection 
on the first day of the relearning activity. 

C. Summary. 
In treating the experimental results of our study of retroaction, 
we refrained from making any general conclusions. We have 
dealt thus far mainly with the factual material. We shall now 
summarize the results under two headings, and make our gen- 
eral conclusions. 

I. Retention. 

1. The groups exhibit a wider range of individual variability 
in relearning a maze than in its original mastery. But two ex- 
ceptions to this generalization were found in y8 cases of com- 
parison. This greater variability is not a function of the maze, 
the kind of subject, nor is it dependent upon the type of activity 
interpolated between the learning and relearning. It is primarily 
a function of the individual's susceptibility to the disintegrating 
effect of time. 

2. There is no correlation between the learning and relearning 
records. The majority of the correlation values are too small 
to be significant; neither are they consistently positive or nega- 
tive. Of 78 cases, 44 were positive, 30 negative and 4 cases 



78 LOUIE WIN FIELD WEBB 

showed zero values. Subjects manifesting good ability in mas- 
tering a maze may thus do poorly in relearning the same maze. 
The individual differences either in mastering or relearning a 
maze are thus due to chance rather than representing individual 
differences in ability. Neither is there any correlation between 
learning records and retentive capacity. Both quick and slow 
learning groups may exhibit the maximum of retentive capacity, 
and both classes may be equally susceptible to the disintegrating 
effects of time. This relation between acquisition and retentive 
capacity is not dependent upon the type of subject, nor upon the 
character of the intervening activity. 

3. Human subjects manifested a slightly greater retentive 
capacity of sensori-motor habits than did the rats. This con- 
clusion is based upon a comparison of the relearning records of 
rat and human subjects for the same mazes, viz. A, B, C, and D. 
Only those subjects employed to test the disintegrating effect of 
time were used in this comparison. 

A greater percent of rat subjects showed some disintegration 
in three of the four maze comparisons. For Maze C a larger 
percentage of the human subjects evidenced some degree of dis- 
integration. Of the subjects that forgot part of the habit during 
the interval, the average relearning records for all three criteria 
of measurement are larger for the rats for Mazes A and B ; the 
same condition prevails for Maze D for errors and time, and 
for Maze C for time alone. Thus the rats have the larger aver- 
ages in 9 of the 12 comparisons. Considering the rats and hu- 
mans as single groups, the averages for the rats are larger by 
all three criteria. The average percentage of loss is on the whole 
larger for the animals. The rats have the larger values by the 
three criteria for A and B, and by errors for Maze D. The 
humans manifested a higher percentage of loss by all three 
criteria on Maze C, and on Maze D by trials and time. The 
average of the percentage values for the rats and humans as 
single groups is the larger for the animals by errors only, the 
humans having larger values for trials and time. This result 
is perhaps due to the fact that the human group on ]\Iaze D 
exhibited a very high percentage of loss by trials and time, due 



TRANSFER OF TRAINING AND RETROACTION 79 

to an individual peculiarity. In the first day's activity in the 
tests for retention, the rats evidenced the greater amount of dis- 
turbance. The averages for the rats are the larger in 5 of the 
8 comparisons. As single groups the rats have the larger values 
for both errors and time. 

4. The degree of retention is a function of the maze activity. 
In comparing the different mazes in respect to retention, we find 
that for human subjects Maze D gives the largest average per- 
centage of loss, and Maze B the smallest percentage of loss by 
all three criteria. A similar condition is noticed to exist with rat 
subjects. To test whether this is a real difference or a mere matter 
of chance, we figured the correlation between the percentage of 
loss due to time and the difficulty of mastery. The mazes were 
arranged in order of their greatest difficulty, and again arranged 
in their order of greatest percentage of loss after a thirty day 
interval. The values for the rats are — .542. — .922, and — .714; 
and for the humans — .400, — .725, and — .800. Thus all of the 
six values are seen to be negative. This means that the maze 
which required the greatest effort to master v^as retained better, 
and that maze requiring the least effort to master manifested the 
greatest percentage of loss; in other words, this means that the 
deeper a motor habit is driven in by prolonged eff'ort, the longer 
and better it will be retained. 

5. A positive correlation exists between any two of the three 
criteria used in measuring retentive capacity. 

The subjects in each group were ranked from the lowest to 
the highest by each of the criteria, and the correlation was com- 
puted between trials and errors, trials and time, and errors and 
time. This procedure gives us 30 correlation values, all of which 
are positive. Of the thirty values, 9 were perfect and 15 were 
above .90; four were between .70 and .80, one .52, and one .38. 
The degree of correlation is not a function of the maze, nor of 
the type of subject employed. The relation between any one 
pair of criteria is no more significant than that existing between 
any other pair. These results indicate that we can utilize one, 
any two, or all three criteria in the measurement of retentive 
capacity and obtain practically the same results. 



8o LOUIE WIN FIELD WEBB 

II. Retroaction. 

I. The greater degree of disintegration occurred for the test 
groups. This result indicates that negative retroaction was pres- 
ent in our experiments. The difference is not great, but it is 
consistent for all rubrics of comparison for both rats and hu- 
mans, and in both experiments. The validity of the conclusion 
must be based primarily upon the consistency of the results. 
The acquisition of any maze activity must thus be regarded as 
exerting some disintegrating effect upon maze habits previously 
mastered. The evidence in support of the above conclusion 
follows. 

(a) On the average a greater percent of subjects was affected 
in the test series. This result obtained for both humans and rats 
in both experiments. The test series manifested the larger per- 
centage in 3 of the 5 mazes for rats in both experiments, and in 
2 of the 3 mazes for humans in each of the experiments. 

(b) Limiting the comparison to those subjects affected, the 
rats exhibited the greater disintegration in the test series stated 
in absolute terms, in 5 of the 6 comparisons. The humans also 
exhibited the greater disintegration by all three criteria of meas- 
urement for both experiments. Considering the mazes as units, 
the humans gave the poorer records in the test series in each of 
the 18 instances of comparison. Likewise, the rats made poorer 
records in the test series in 20 of the 30 comparisons. 

(c) The test series gave the poorer records in both experi- 
ments when the results are stated in relative, or percentage terms ; 
that is, the test series exhibited the greater percentages of loss. 
The rats as a group gave the poorer average records for both 
errors and time in each of the experiments. The records for 
the humans were the poorer by all three criteria for both experi- 
ments. Considering the mazes as units, the humans gave the 
poorer records in each of the 18 instances of comparison, and 
the rats for 19 of the 30 cases. 

(d) The average amount of retracing was the greater in the 
test series for both humans and rats in both experiments. The 
retracing for the rats was the greater for 9 of the 10 mazes, and 
for 5 of the 6 mazes with the human subjects. 



TRANSFER OF TRAINING AND RETROACTION 8i 

(e) The greater disintegration occurred in the test series when 
measured by the records of the initial trials. This result ob- 
tained for the rats as a whole in 4 of the 5 instances of compari- 
son, and for the humans in 2 of the 3 comparisons, in both ex- 
periments; it was likewise true for the rats in 9 of the 10 mazes, 
and for the humans in 4 of the 6 mazes. 

2. The existence of retroaction is a function of the individual. 
In practically every group in both experiments, some subjects 
were affected and some were not. Of the total number of sub- 
jects employed in the first experiment, 37% manifested no dis- 
integration, and in the second experiment 26.7% of the subjects 
gave no evidence of a disturbing effect. 

3. Human subjects are more susceptible than rats to the dis- 
integrating effect of retroactive influences. 

For purposes of this comparison, we shall utilize only the rec- 
ords for Mazes A, B, C, and D upon which both rat and human 
subjects w^ere employed. This gives us six cases of comparison, 
three in each experiment. To determine the amount of retro- 
action present in each test, we subtracted the records of the con- 
trol group from those of the test group; the difference may be 
said to be due to retroaction. Upon a basis of a comparison 
of these results, we have the follow- ing evidence in support of 
the above conclusion. 

A larger percentage of the human subjects manifested some 
degree of negative retroaction. The percentages are considerably 
larger for the humans in 4 of the 6 cases. The two exceptions 
are found in noting the effect of B upon A and of A upon B; 
the relative susceptibility of the two groups may thus be a func- 
tion of the maze. In three of the human groups 100% of the 
subjects were affected, while in no instance did any of the rat 
groups have all of the subjects affected. 

Stated in absolute terms, the average amount of disturbance 
for the human subjects is the larger in all six of the mazes. In 
the 18 instances of comparison, the values are the larger in the 
human records in 17 cases. Taking the groups as units in the 
first and second experiments, the humans have the larger aver- 
ages in all six comparisons. 



^2 LOUIE UlNFIELD WEBB 

Making the comparison in terms of percentage of loss, we 
find that the humans manifested a greater degree of disintegra- 
tion in all six mazes, and by all i8 instances of measurement. 

The human subjects manifested the greater disturbance as 
measured by the amount of retracing. The average for the 
humans is larger in four of the six mazes. Considering the sub- 
jects in each experiment as units, the averages are much larger 
in both cases for the human subjects. 

In the first day's activity of the relearning tests, the humans 
evidenced a greater disturbance in 4 of the 6 mazes when meas- 
ured by errors, and in 2 of the 6 mazes when measured by time. 
The result by time may readily be attributed to the fact that 
the rats in returning to a maze problem after an interval of sev- 
eral days are c[uite cautious at first and travel rather slowly. 

4. A positive correlation was found to exist between any 
two of the criteria employed in measuring the retroactive effect. 
The ranking method was used, and the values were determined 
for trials and errors, trials and time, and errors and time. In 
this manner we secured 12 values evenly divided between the 
rats and humans. Nine of the 12 values are positive. The 
validity of the conclusion depends upon the consistency of the 
positive values. This result is not a function of the maze, nor 
the type of subject. A much closer and more significant relation 
exists between errors and time than between any other pair. Of 
the four values measuring this relation, three are perfect and one 
.70, while none of the other values are above .50. In measuring 
the retroactive effect of one maze activity upon another, we can 
thus utilize one, two. or three of the criteria without materially 
changing the results. 

5. Direction is not a deciding factor in determining the 
amount of retroaction present. The manner in which our ex- 
periment was arranged makes it possible to determine whether 
the retroactive effect of two activities upon each other was the 
same or dift'erent; thus we have the retroactive effect of x\ upon 
B, and of B upon A, and so with the other pairs of mazes. No 
new data are needed; a comparison of the data employed in 
determining the amount of retroaction present supports the above 



TRANSFER OF TRAINING AND RETROACTION 83 

conclusion. When the mazes are ranked according to the amount 
of retroaction present, we find that in both directions with rat 
subjects A and F stand first, and A and D last. Each of the 
other three pair has a slightly different rank according to direc- 
tion. In the human records we have a similar result. The largest 
disturbing effect occurred between A and C in both directions, 
while the rank in the other two pairs of mazes dift'ers slightly 
for the two directions. As a matter of chance, we would expect 
some difference due to the change of direction. We believe that 
the fact that three pairs of mazes are not affected by the change 
of direction is more significant than the difference in the other 
pairs, and that the above conclusion is justified. fj 

6. The degree of retroaction is a function of the interpolated ; 
maze activity. The easier is the maze to learn, the greater is • 
the resulting negative retroaction. The various mazes were 
ranked in their order of difficulty of mastery. These were also 
ranked in order as to their retroactive effect. Correlation values 
between the two values were computed. Five of the six values 
are negative, three of which are perfect and two above .60. 

A positive retroactive effect was secured for Mazes A and D 
with rat subjects. The interpolation of A was beneficial upon 
the remastery of D by all three criteria. Likewise D exerted 
a favorable effect upon the relearning of A by all three criteria. 
This fact indicates that retroaction may be positive in character 
with some pairs of mazes. Additional evidence in support of 
the above conclusion is had as a result of computing the correla- 
tion between transfer and retroaction. These values will be dis- 
cussed in the following topic. 

7. There is a negative correlation between positive transfer 
and negative retroaction. Those conditions which produce the 
maximum amount of positive transfer give the least amount of 
negative retroaction. We ranked the mazes according to the 
percent of transfer present in both of the experiments dealing 
with that topic. We also ranked the mazes according to the 
amount of negative retroaction present determined by subtracting 
the records of the control groups from those of the test groups. 
From these ranks we computed the correlation between mazes; 



84 LOUIE IVINFIELD WEBB 

in the first instance the correlation is between A-B etc. in the 
transfer and A-B etc. in the tests for retroaction, while in the 
other case the values are between the records of A-B etc. in the 
transfer and ^-A etc. in the retroaction. This was done for 
both experiments, thus giving us 24 values in all. Twenty-one 
of the values are negative, 5 of which are perfect, 7 are — .70 
or above, and the remaining values are around — .50. These 
results mean that the greater the assistance rendered by the first 
maze experience in the mastery of the second maze, the less 
disturbance will there be in relearning the first maze. 

The same relation between retroaction and transfer is ap- 
parent from a comparison of the rat and human subjects. The 
rats manifested a greater ability than did the humans in the 
transfer experiments, while they exhibited the lesser suscepti- 
bility to retroactive disturbances. 

D. Theoretical Discussion. 

Two explanatory conceptions of retroaction which possess 
some degree of logical plausibility may be suggested. 

1. The Transfer Hypothesis. This conception has been sug- 
gested by DeCamp. The retroactive effect is regarded as a case 
of transfer. In the maze sequence A-B-A, the term retroaction 
refers to the eft'ect of the acquisition of the B habit upon the 
subsequent functioning, or relearning of the A habit. The trans- 
fer hypothesis assumes that this effect is mediated by the simple 
transference of certain elements of the B habit to the succeeding 
maze A situation. Theoretically this transference may operate 
either in an advantageous or detrimental manner ; in other words 
retroaction may be positive or negative. 

2. The Disruption Hypothesis. In the maze sequence of 
A-B-A, Ave know that transfer obtained in proceeding from A 
to B. Certain elements of the complex A habit have been trans- 
ferred to and utilized in the maze B situation. The hypothesis 
assumes that this incorporation of certain components of the 
A habit into the subsequently acquired B habit must necessarily 
involve its partial disruption and disorganization. The A 
habit is a complex system whose component elements have been 



TRANSFER OF TRAINING AND RETROACTION 85 

welded and associated into a unitary whole. The utilization of 
certain of its parts in a new situation must involve their dissocia- 
tion from their former contextual relations, and the habit must 
thus be partially disrupted and disorganized. The remastery of 
A after the acquisition of B must repair not only the ravages 
due to time, but dissociate these elements from their new context 
and weld them anew into their original system of relations. Ac- 
cording to the disruption hypothesis, the retroactive effect will 
invariably be negative in character. 

The two hypotheses are not antagonistic or mutually exclusive. 
They may supplement each other. The effect of the B habit 
upon the functioning, or remastery of A may be due in part to 
the process of disruption, and in part to the transference of cer- 
tain components of the B habit which are carried over to the 
subsequent A situation. 

Several of our factual data are relevant to a consideration of 
the validity of the disruption hypothesis. 

1. Transfer was present for all pairs of mazes employed in 
our experiments, and some degree of retroaction was manifested 
for each of these maze situations. This fact supports the 
hypothesis, for it assumes that retroaction is a necessary by- 
product of the previous transfer process. 

2. All subjects, both human and animal, manifested the 
phenomenon of transfer, yet a certain percentage of these indi- 
viduals (33) were not subject to any retroactive effect. This 
fact constitutes a serious objection to the acceptance of the 
hypothesis. These individual exceptions can be explained by the 
supposition that the retroactive effect is the combined result of 
both disruption and positive transfer, and that these two an- 
tagonistic tendencies were equal in these particular cases. 

3. According to the hypothesis, retroaction will invariably be 
negative in character. Our results support this assumption in 
fourteen of the sixteen pairs of mazes. The pair A-D consti- 
tutes a possible exception with the animal subjects. We have 
previously indicated that there are good reasons for concluding 
that the retroactive effect was positive for this pair of mazes. 

4. Transfer and retroaction are inversely correlated; those 



86 LOUIE \V INFIELD WEBB 

conditions which give the greatest amount of positive transfer 
give the least subsequent negative retroactive effect. This fact 
presents some difficulty to the hypothesis, for it is logical to sup- 
pose that the degree of disruption will vary directly with the 
degree of transfer. This apparent exception to the validity of 
the theory may be obviated by the following mode of explana- 
tion. Both positive and negative transfer will produce a dis- 
ruption of the first habit, and thus mediate a negative retroactive 
effect. We may assume that the disrupting effect of negative 
transfer will be greater than in the case of positive transfer. 
Our experiments on the transfer phenomenon have demonstrated 
that the total transfer effect is the sum of both positive and nega- 
tive elements, although the positive factor predominated in every 
case. This conception explains the varying degree of transfer 
for the different conditions under which the experiments w^ere 
conducted. The total effect is minimal when the negative factors 
approximate the positive in strength. The greatest total effect 
is achieved when the relative functional efficiency of the positive 
factors is at a maximum. Granted that the negative factors 
possess the greater disrupting efficacy, it is thus possible for the 
degree of disruption, and hence for the degree of retroaction, 
to be inversely related to the degree of transfer. 

5. The retroactive effect was manifested on the first day's 
trials. This initial inefficiency of the A habit in the test group 
as compared with the control group indicates the presence of 
some previous disrupting or disorganizing process. The fact 
can, however, be easily explained in terms of the transfer 
hypothesis. 

The following facts are pertinent to a consideration of the 
validity of the transfer hypothesis concerning the nature of the 
retroactive effect. 

I. The retroactive effect was negative in fourteen of the six- 
teen pairs of mazes. If this effect is mediated by a transfer 
process, we are forced to conclude that this transfer was nega- 
tive in the majority of cases. The same pairs of mazes w^ere 
utilized in the transfer experiments and the effect was positive 
in every case. In other words, the hypothesis assumes that 



TRANSFER OF TRAINING AND RETROACTION 87 

transfer is negative when previous experiments on the same 
mazes have demonstrated that the effect is positive. 

A certain percentage of subjects manifested no retroactive 
disturbance, and yet all subjects lexhibited transfer for the same 
pairs of mazes. The hypothesis is thus forced to reconcile the 
occasional absence of transfer in the one experiment with its 
invariable presence in the other, the same pairs of mazes being 
used in both cases. 

The above facts, however, do not disprove the transfer con- 
ception of the retroactive effect, for the two experiments differed 
in several important respects, although the same pairs of mazes 
were employed in both, a) In the transfer experiments we were 
concerned with the effect of the first habit upon the acquisition 
of a second activity. The retroactive experiment was concerned 
with the effect of a second habit upon a third activity. In a 
series of successive activities, it is possible that positive transfer 
may obtain for the first pair while a negative effect will be ex- 
hibited by all succeeding pairs of the sequence. Some recent 
experiments in this laboratory, however, have disproved this as- 
sumption; some degree of positive transfer was invariably ob- 
tained in a sequence of five maze activities, b) The transfer 
experiment was concerned with the effect of a maze habit upon 
the original mastery of a second maze; retroaction refers to the 
effect of a maze habit upon the remastery of a second maze. In 
the one case, we are concerned with the utilization of a habit in 
the development of a new habit, and in the other with its utiliza- 
tion in the perfection of an old habit. The character of the 
transfer process may differ radically in the two cases. There 
are two considerations which support this assumption, (i) In 
the transfer experiments the subjects first develop the maze A 
habit. They are now transferred to a similar situation, viz.. 
Maze B. This new sensory situation, because of its similarity, 
arouses or stimulates certain components of the previous A habit. 
The conditions of the retroactive experiment are radically dif- 
ferent. The subjects have acquired two habits, A and B, in suc- 
cession. They are now transferred back to the old Maze A. This 
sensory situation now tends to rearouse both the A and B habits. 



88 LOUIE WIN FIELD WEBB 

Conflict and interference between the two systems must 
be the logical result. The conflict may apply to the 
process of recall, the transfer of the B habit operating 
to repress or to prevent the rearousal of the A habit 
which is to be remastered. Certain components of both 
systems may be reinstated and the conflict will result from their 
functional antagonism. In either case, confusion and an in- 
creased difticulty of mastery will result. In other words, trans- 
fer will be detrimental in the remastery of a maze although 
beneficial in its original mastery. (2) The transfer experiment 
demonstrated that the transfer efifect was limited almost ex- 
clusively to the early stages in the development of a habit. The 
process of transference starts the subjects at an advanced stage 
of the problem and exerts relatively little effect upon the final 
development of the habit. In other words, transference exerts 
radically different effects upon the initial and the final stages 
in the development of a habit. In the retroactive experiment 
we are dealing with the remastery of a partly disintegrated habit. 
The habit is largely retained, the subjects are introduced to the 
problem at an advanced stage of mastery, and the process of re- 
learning is essentially similar to the final stages of the develop- 
ment of a new habit. This fact is evident from a comparison 
of the curves of learning with those of relearning in the tests 
for retention. The relearning curves do not exhibit the pro- 
nounced initial descent characteristic of the typical learning 
curve; they approximate in character the latter part of the normal 
curve. Since transference exerts radically different effects upon 
the initial and the final stages of learning, one can not assume 
that transfer must produce the same effects in our two experi- 
ments; in fact one must assume that the effects are essentially 
different. 

2. The transfer experiment does prove, however, that trans- 
ference of some sort is always in evidence throughout a sequence 
of maze activities, and necessitates the conclusion that transfer 
of some kind did occur in the retroactive experiments, although 
it will not justify any assumptions as to the nature and degree 
of these effects. 



TRA.XSFER OF TRAINING AND RETROACTION 89 

3. The existence of a transfer process in the retroactive ex- 
periment is proven beyond doubt by certain facts which have 
been described on page 68. As previously noted, Mazes A and F 
were so designed in relation to each other that any transference 
from one to the other is easily detected. Both possess a common 
section 6-10. This section constitutes a part of the true pathway 
in A, but it is one of the cul de sacs in F. In the retroactive 
sequence of F-A-F, the subjects are first required to avoid this 
section, then to develop the habit of entering it in A, and then 
to avoid it again in the mastery of F. If the habit of entering 
this section acquired during the mastery of A is transferred to 
the subsequent F situation, it will be manifested by a greater 
number of entrances into this section than are made by the con- 
trol group that has been given the maze sequence F — F. Such 
results were, in fact, secured. The average number of entrances 
into this section by the test and control groups respectively was 
11.25 3.nd 1. 71. The corresponding number of trials in which 
this section was entered was 7.62 and 1.42. The number of 
trials necessary to eliminate this tendency was 10.35 ^^^d .085 
for the test and control groups respectively. The total error 
scores made in this section for the two groups were 35.37 and 
5.28. All of the above values are also much larger for the test 
group when stated in percentage terms. 

These facts prove not only that a transference process does 
exist in the retroactive experiment but also that it was negative 
in character for the maze sequence F-A-F. It is also well to 
note that the greatest negative retroactive effect was secured for 
this particular pair of mazes. 

4. The negative retroactive effect was evident in the first 
day's trials. This fact can be explained by the hypothesis. Our 
experiment demonstrated that the process of transference was 
more effective upon the initial trials than upon the later stages. 
If the negative effect is due to the confusion or conflict between 
the two systems of habits, this confusion will necessarily be 
present at first. 

To summarize : The existence of a negative transference 
process has been demonstrated for one pair of mazes in the 



go LOUIE WIN FIELD WEBB 

retroactive experiment; the situations in our two experiments 
are so different that one is justified in assuming (unless proof 
to the contrary is advanced) that both sets of results were 
mediated by transfer; all of our factual data concerning the 
phenomenon of retroaction are readily explicable in terms of 
the transfer conception. On the other hand, there is no positive 
proof of the existence of a disrupting process. The conception 
explains some facts quite readily, some with difficulty, while 
others are incapable of explanation in such terms. We are thus 
forced to conclude that 'the retroactive eft'ect is to be explained 
mainly, if not wholly, in terms of transfer, although it may be 
due in part to a process of disruption. It is well to remark that 
retroaction in so far as it can be reduced to transfer can not be 
regarded as a phenomenon siii generis. 



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